Hook and loop strap for riders who need help with keeping their knees inward so that the hamstring muscles can push down against the pedals. Adductor strap available in three sizes. The sizing process starts with a circumference measurement of the thigh just above the knee. Small strap will fit 6-9 inch circumference. Medium strap will fit 10-14 inch circumference. Large strap will fit 15-19 inch circumference.