Super Quick Fist clamp holds objects 2-1/2-inches to 9-1/2-inches (64 millimeters to 240 millimeters) in diameter. Mounts easily. Each clamp supports a safe working of 50 pounds (23kilos). Ideal for air tanks, fire extinguishers, nitrous oxide tanks, scuba tanks, etc. Each clamp supports a safe working load of 50 pounds (23 kilos). 2 Clamps support 100 pounds (45 kilos). Mounts with three #10 bolts or screws. Mounting area: 6-inches x 7/8-inches (152 x 22 millimeters).