Monument 173 has been especially designed for removing stiff backnuts from awkward placed taps and to make tap installation a more rapid process, this tool is for 1/2-inch. BSP and 3/4-inch. BSP taps. The Monument 170 tool stays in position on the tap tail so can be used with one hand and uses mechanical advantage of the thread of the tap tail to remove stiff nuts. Ideal for 1/2-inch and 3/4-inch BSP 25 mm 27 mm nuts 29 mm ribbed 32 mm nuts. The MON173 is complete with 3/8-inch cordless drill adaptor, 1/2-inch square drive, extension tube and full user instructions. For removing stiff backnuts and rapid tap installation for 1/2-inCH. BSP and 3/4-inch. BSP Taps.Tool stays in position on the tap tail. Uses mechanical advantage of the thread of the tap tail to remove stiff nuts. Monument Stiffnuts Professional Boxed Kit. 1/2-inch. and 3/4-inch. BSP 25 mm 27 mm nuts 29 mm ribbed 32 mm nuts. Complete with 3/8-inch. Cordless drill adaptor, 1/2-inch. Square Drive; Extension tube and full instructions.