Hit Air Buckle ExtendersWe love these Hit Air Buckle Extenders because they add up to 7 extra inches for the chest strap and 6. 25 extra inches for the waist strap. Normally used when wearing a HitAir Vest over top a traditional hard safety vest. Also helpful for people with larger frames to give a little extra room in the vest. The Hit Air Buckle Extenders can be used to adjust the fit of Hit Air Vest to ensure a perfect fit. Vest Model specific, cannot be used on Zipper