This locking pinch-off tool is clamped and locked to the copper tube so that both hands can freely do other work. Adjustment screws provide tight pressure. The jaw opening and clamping pressure can be changed simply by turning the adjusting screw. It remains adjusted for reuse. A guaranteed release trigger helps keep your work safe. It will be released and unlocked quickly when needed. The locking clamp has a very powerful locking mechanism. Made of high-grade alloy steel, heat treated for maximum toughness and durability.