TURNS DUMBBELLS INTO KETTLEBELLS IN A SNAP: Simply, open hinged handle, place your own dumbbell into the grip, re-close handle, snap latch. Kettle Gryp has the #1 patented secure latching closure. Easy. Safe. Secure. DUMBBELL COMPATIBILITY: Compatible with most adjustable dumbbells and nearly all standard dumbbells with bare metal handles (max 1.5" handle diameter, min 4.5" handle length). **Does not fit** most vinyl or neoprene coated dumbbell handles because those are often too thick and/or too short. Please refer to the compatibility graphics.