Fit Cuffs – Arm Cuff V3 includes a single cuff that has the same width as the original Arm Cuff, but engineered for even faster attachment as state-of-the-art exclusively developed for Blood Flow Restriction (BFR) Exercise. Fit Cuffs works by inflating solid yet pliable cuffs by means of a solid pressure gauge and solid metal quick-disconnectors. It will fit about all arm sizes (Arm Cuff 20-50 cm / 7.9-20 Inch). One-Size-Fits-All. You need the Fit Manometer (pressure gauge) to use the Arm Cuff V3.