This version is a bit thicker, and has 2 pieces that slide into the base piece to make the bidirectional catch. Each of the inserts has a stop and a catch on one side, and the other side is smooth. The smooth sides should be adjacent when inserting them. Look at your original piece to see which way the longer piece sticks out before gluing it together. I printed with ABS and it is slightly flexible and has lasted longer than the original, which cracked right where the base joins the longer catch. The wider part of the base with the ridge goes against the rail, and slides into place.