The SkyEcho is a portable device that you can take with you from aircraft to aircraft and does not require physical or electrical installation into the airframe.  EC devices use a 24-bit address in the same way as a transponder.  This usually forms part of an aircraft's Certificate of Registration.  However, as an EC device is designed to be portable and to also be used by unregistered aircraft, the 24-bit address will be programmable by the user.   The device is small enough to sit on your glare shield and fit easily in your flight bag.
Refer to the guidelines under the section titled “How to use 24-bit addresses with Electronic Conspicuity Devices” section available on the Electronic Conspicuity page.