A filler panel, comprising: a panel body that includes: (i) first and second latching members (120a, 120b), each defining a hood portion, wherein each hood portion includes an angled, stepped latching surface (124a, 124b); (ii) two or more guide posts (130a, 130c); and (iii) two or more locator walls (140a, 140c) positioned proximal to and spaced from each guide post (130a, 130c), each locator wall (140a, 140c) attached to the panel body; wherein the panel body extends from a first end to a second end, the first end including the first latching member and the second end including the second latching member; wherein each guide post (130a, 130c) has a top portion (134a, 134c) that extends further from the panel body than its proximal locator wall (140a, 140c) extends from the panel body; wherein the angled, stepped latching surface (124a, 124b) associated with each hood portion defines a plurality of stepped surfaces. wherein the top portion (134a, 134c) of each guide post (130a, 130c) is configured to enter and fill a round hole associated with a first railing and guide at least one of the latching members (120a, 120b) to engage the first railing while its proximal locator wall (140a, 140c) cannot enter the same respective round hole; wherein a second railing defines a plurality of square holes; and wherein after each guide post (130a, 130c) has entered a round hole associated with the first railing and thereafter removed from each respective round hole, then each locator wall (140a, 140c) and its proximal guide post (130a, 130c) are both configured to enter the same respective square hole defined in the second railing and to guide at least one of the latching members (120a, 120b) to engage the second railing. a panel body that includes: (i) first and second latching members (120a, 120b), each defining a hood portion, wherein each hood portion includes an angled, stepped latching surface (124a, 124b); (ii) two or more guide posts (130a, 130c); and (iii) two or more locator walls (140a, 140c) positioned proximal to and spaced from each guide post (130a, 130c), each locator wall (140a, 140c) attached to the panel body; wherein the panel body extends from a first end to a second end, the first end including the first latching member and the second end including the second latching member; wherein each guide post (130a, 130c) has a top portion (134a, 134c) that extends further from the panel body than its proximal locator wall (140a, 140c) extends from the panel body; wherein the angled, stepped latching surface (124a, 124b) associated with each hood portion defines a plurality of stepped surfaces. wherein the top portion (134a, 134c) of each guide post (130a, 130c) is configured to enter and fill a round hole associated with a first railing and guide at least one of the latching members (120a, 120b) to engage the first railing while its proximal locator wall (140a, 140c) cannot enter the same respective round hole; wherein a second railing defines a plurality of square holes; and wherein after each guide post (130a, 130c) has entered a round hole associated with the first railing and thereafter removed from each respective round hole, then each locator wall (140a, 140c) and its proximal guide post (130a, 130c) are both configured to enter the same respective square hole defined in the second railing and to guide at least one of the latching members (120a, 120b) to engage the second railing.