Knurled Knob Swivel Screw Clamp With Small Pad – 1/2-13 Thread X 2-15/16. For Use When Finger Tightening Provides Adequate Pressure. Pad Can Pass Through Tapped Hole. Pad Swivels In All Direction, And Makes Maximum Contact With Angled Of Uneven Surfaces. When Pad Comes Into Contact With Part Or Workpiece, It Stops Rotating And Thus Prevents Marring. Black Oxide Finish.