Designed for use with taps and on many other tools to be turned by hand. Adjusted and tightened to size by twisting knurled nut. Additional holding jaws are recessed inside hole for gripping onto smaller sized taps. T-handle may be extended full length in either direction for more leverage. Tap wrench size : TR-1E for taps no. 0 to 1/4" (3mm to 6mm).