Can other balusters be used instead of trex for this system

Hello, and thank you for your interest in Trex! The listed Trex accessory infill kit a.k.a railing completer kit is designed for Trex's square composite baluster dimensions. Therefore Trex does not recommend using other balusters, however as long as you find balusters identical in dimension they would fit into the pre-made holes. I hope this helps answer your question. Thanks, Tori - Trex Customer Care Team