The plastic leg support will fit any Toddler Table brand seat produced in 2008 or later. From underneath the seat, slide each side of the leg support up until the round pegs fit cleanly in the slots on the leg support.
Make sure that the two support bars are squarely in the slot provided in the leg support. Once you have fitted the leg support onto the seat, turn the seat over while holding the leg support in place and push the seat and leg support into the seat hole of the Toddler Table. Check to make sure that the seat is all the way down into the seat hole, which means that the leg support is properly in place.