Designed for use with taps, reamers, screw extractors and other tools with a square shank. Adjusted and tightened to size by twisting knurled nut. TR-2E Tap Wrench For Taps 1/4" to 1/2" (6mm to 12mm) Designed for use with taps, reamers, screw extractors and other tools with a square shank Adjusted and tightened to size