The Competitor Choke Tube Wrench is designed for 12 Gauge Shotguns. The Thumb screw adjustment makes a tight fit possible for removing stubborn choke tubes. The crank handle provides extra torque and comfort. The compact size makes storage easy. For 12 Gauge only. Made from Aluminum, Steel and plastic: Approximate Dimensions 2.75 x 3 inches. NOTE: if the choke tube will not come out, it may have been cross-threaded during installation or it may have rusted in place. Try applying Breakthrough Clean Technologies® Carbon Pro or Military Grade Solvent around the choke tube to loosen it. If the choke tube still does not come out, it may require gunsmithing. TIP: before reinstalling the choke tube, apply light grease, like Breakthrough Clean Technologies® Battle Born™ Grease. This will ensure that the choke tube can be easily removed.