Exhibit
4.13


 


Description
of Capital Stock


 


The
following description of our common stock and preferred stock, together with the additional information we include in any applicable
prospectus supplements, summarizes the material terms and provisions of our common stock and preferred stock. The following description
of our capital stock does not purport to be complete and is subject to, and qualified in its entirety by, our certificate of incorporation
and bylaws, and by applicable law. We have filed copies of our certificate of incorporation and bylaws with the SEC. The terms
of our common stock and preferred stock may also be affected by Delaware law.


 


Authorized
Capital Stock


 


Our
authorized capital stock consists of 250,000,000 shares of common stock, par value $0.001 per share, and 25,000,000 shares of
preferred stock, par value $0.001 per share. As of March 15, 2021, we had 80,255,426 shares of common stock outstanding and no
shares of preferred stock outstanding.


 


Common
Stock


 


The
holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of the stockholders.
The holders of our common stock do not have any cumulative voting rights. Holders of our common stock are entitled to receive
ratably any dividends declared by our board of directors out of funds legally available for that purpose, subject to any preferential
dividend rights of any outstanding preferred stock. Our common stock has no preemptive rights, conversion rights or other subscription
rights or redemption or sinking fund provisions.


 


In
the event of our liquidation, dissolution, or winding up, holders of our common stock will be entitled to share ratably in all
assets remaining after payment of all debts and other liabilities and any liquidation preference of any outstanding preferred
stock. All outstanding shares are fully paid and non-assessable.


 


Preferred
Stock


 


Our
board of directors is authorized to issue up to 25,000,000 shares of undesignated preferred stock in one or more series without
stockholder approval. Our board of directors may determine the rights, preferences, privileges, and restrictions, including voting
rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock.


 


The
purpose of authorizing our board of directors to issue preferred stock in one or more series and determine the number of shares
in the series and its rights and preferences is to eliminate delays associated with a stockholder vote on specific issuances.
Examples of rights and preferences that the board of directors may fix are:


 


	 	●	dividend
    rights;
	 	●	conversion
    rights;
	 	●	voting
    rights;
	 	●	preemptive
    rights;
	 	●	terms
    of redemption;
	 	●	liquidation
    preferences;
	 	●	sinking
    fund terms; and
	 	●	the
    number of shares constituting, or the designation of, such series, any or all of which may be greater than the rights of common
    stock.


 




    	 



    	 



    




 


The
existence of authorized but unissued shares of undesignated preferred stock may enable our board of directors to render more difficult
or to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest, or otherwise. For example,
if in the due exercise of its fiduciary obligations, our board of directors were to determine that a takeover proposal is not
in the best interests of us or our stockholders, our board of directors could cause shares of preferred stock to be issued without
stockholder approval in one or more private offerings or other transactions that might dilute the voting or other rights of the
proposed acquirer, stockholder, or stockholder group. The rights of holders of our common stock described above, will be subject
to, and may be adversely affected by, the rights of any preferred stock that we may designate and issue in the future. The issuance
of shares of undesignated preferred stock could decrease the amount of earnings and assets available for distribution to holders
of shares of common stock. The issuance may also adversely affect the rights and powers, including voting rights, of these holders
and may have the effect of delaying, deterring, or preventing a change in control of us.


 


Antitakeover
Effects of Delaware Law and Provisions of our Restated Certificate of Incorporation and Amended and Restated Bylaws


 


Certain
provisions of the Delaware General Corporation Law and of our restated certificate of incorporation and amended and restated bylaws
could have the effect of delaying, deferring or discouraging another party from acquiring control of us unless such takeover or
change of control is approved by the board of directors. These provisions, which are summarized below, are expected to discourage
certain types of coercive takeover practices and inadequate takeover bids and, therefore, they might also inhibit temporary fluctuations
in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions are
also designed in part to encourage anyone seeking to acquire control of us to first negotiate with our board of directors. These
provisions might also have the effect of preventing changes in our management. It is possible that these provisions could make
it more difficult to accomplish transactions that stockholders might otherwise deem to be in their best interests. However, we
believe that the advantages gained by protecting our ability to negotiate with any unsolicited and potentially unfriendly acquirer
outweigh the disadvantages of discouraging such proposals, including those priced above the then-current market value of our common
stock, because, among other reasons, the negotiation of such proposals could improve their terms.


 




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Delaware
Takeover Statute. We are subject to the provisions of Section 203 of the Delaware General Corporation Law. In general, Section
203 prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested
stockholder” for a three-year period following the time that this stockholder becomes an interested stockholder, unless
the business combination is approved in a prescribed manner. Under Section 203, a business combination between a corporation and
an interested stockholder is prohibited unless it satisfies one of the following conditions:


 


	 	●	before
    the stockholder became interested, our board of directors approved either the business combination or the transaction which
    resulted in the stockholder becoming an interested stockholder;
	 	●	upon
    consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder
    owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for
    purposes of determining the voting stock outstanding, shares owned by persons who are directors and also officers, and employee
    stock plans, in some instances, but not the outstanding voting stock owned by the interested stockholder; or
	 	●	at
    or after the time the stockholder became interested, the business combination was approved by our board of directors and authorized
    at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds of the outstanding voting
    stock which is not owned by the interested stockholder.


 


Section
203 defines a business combination to include:


 


	 	●	any
    merger or consolidation involving the corporation and the interested stockholder;
	 	●	any
    sale, transfer, lease, pledge, exchange, mortgage or other disposition involving the interested stockholder of 10% or more
    of the assets of the corporation;
	 	●	subject
    to exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation
    to the interested stockholder;
	 	●	subject
    to exceptions, any transaction involving the corporation that has the effect of increasing the proportionate share of the
    stock of any class or series of the corporation beneficially owned by the interested stockholder; or
	 	●	the
    receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits
    provided by or through the corporation.


 


In
general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the outstanding
voting stock of the corporation and any entity or person affiliated with or controlling or controlled by the entity or person.


 


Provisions
of our Restated Certificate of Incorporation and Amended and Restated Bylaws. Our restated certificate of incorporation and
amended and restated bylaws include several provisions that may have the effect of delaying, deferring or discouraging another
party from acquiring control of us and encouraging persons considering unsolicited tender offers or other unilateral takeover
proposals to negotiate with our board of directors rather than pursue non-negotiated takeover attempts. These provisions include
the items described below.


 


Board
composition and filling vacancies. In accordance with our restated certificate of incorporation, our board is divided into
three classes serving staggered three-year terms, with one class being elected each year. Our restated certificate of incorporation
also provides that directors may be removed only for cause and then only by the affirmative vote of the holders of two-thirds
or more of the shares then entitled to vote at an election of directors. Furthermore, any vacancy on our board of directors, however
occurring, including a vacancy resulting from an increase in the size of our board, may only be filled by the affirmative vote
of a majority of our directors then in office even if less than a quorum.


 




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No
written consent of stockholders. Our restated certificate of incorporation provides that all stockholder actions are required to
be taken by a vote of the stockholders at an annual or special meeting, and that stockholders may not take any action by written consent
in lieu of a meeting. This limit may lengthen the amount of time required to take stockholder actions and would prevent the amendment
of our bylaws or removal of directors by our stockholder without holding a meeting of stockholders.


 


Meetings
of stockholders. Our bylaws provide that only a majority of the members of our board of directors then in office or stockholders
holding at least one-quarter of the voting power of all the then outstanding shares of our capital stock entitled to vote generally
in the election of directors may call special meetings of stockholders and only those matters set forth in the notice of the special
meeting may be considered or acted upon at a special meeting of stockholders. Our bylaws limit the business that may be conducted
at an annual meeting of stockholders to those matters properly brought before the meeting.


 


Advance
notice requirements. Our bylaws establish advance notice procedures regarding stockholder proposals pertaining to the nomination
of candidates for election as directors or new business to be brought before meetings of our stockholders. These procedures provide
that notice of stockholder proposals must be timely given in writing to our corporate secretary prior to the meeting at which
the action is to be taken. Generally, to be timely, notice must be received at our principal executive offices not less than 45
days or more than 75 days prior to the first anniversary date of the annual meeting for the preceding year. The notice must contain
certain information specified in our bylaws.


 


Amendment
to certificate of incorporation and bylaws. As required by the Delaware General Corporation Law, any amendment of our restated
certificate of incorporation must first be approved by a majority of our board of directors, and if required by law or our restated
certificate of incorporation, must thereafter be approved by a majority of the outstanding shares entitled to vote on the amendment,
and a majority of the outstanding shares of each class entitled to vote thereon as a class, except that the amendment of the provisions
relating to stockholder action, directors, amending our bylaws, limitation of liability and the amendment of our restated certificate
of incorporation must be approved by not less than two-thirds of the outstanding shares entitled to vote on the amendment, and
a majority of the outstanding shares of each class entitled to vote thereon as a class. Our bylaws may be amended by the affirmative
vote of a majority vote of the directors then in office, subject to any limitations set forth in the bylaws; and may also be amended
by the affirmative vote of at least two-thirds of the voting power of all the then outstanding shares of our capital stock entitled
to vote generally in the election of directors, voting together as a single class.


 




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