Trail Gator Tow Bar and Accessories Spare seat post attachment (for the children's bike) for the Trail-Gators Fits all Trail-Gator models including the 640020-640022-640023 Allow the Trail-Gator to be attached to multiple juvenile bicycles quickly Fits headtube up to 45 mm or 1 and 3/4 of an inch Spare seat post attachment (for the children's bike) for the Trail-Gators