The IRWIN QUICK-GRIP 100 Series 4-inch C-Clamp uses a double-rolled thread for faster clamping and increased durability and features a larger swivel pad to reduce marring on work surfaces and increase stability. A larger handle gives greater clamping pressure with less effort and reduced hand fatigue. From the Manufacturer The IRWIN 4" C-Clamp 100 Series has many improvements over the competitions. The handle is bigger which makes it 25% easier to apply torque. This feature will reduce hand fatigue and make it easier to apply force. The double threaded screw allows you to create 50% more pressure than the nearest competitor. This will reduce hand fatigue and make it easier to apply force. The double threaded screw will give you 50% less screw deflection which will save you time by reducing drift.