The BuckleBuster attaches to the loop at the end of the Harness Adjustment Strap. If the strap is too long after adjusting the harness to fit your child properly, you can use the slide buckle included which enables you to adjust the harness adjustment strap so that it can be taut to keep the crotch buckle from getting wedged beneath your child.

The BuckleBuster attaches to the loop at the end of the Harness Adjustment Strap. After adjusting the harness to fit your child properly, and the harness adjustment strap is taut enough to keep the crotch buckle from getting wedged beneath your child, the slide buckle is not needed.