For removing stiff backnuts & rapid tap installation for 1/2in. BSP & 3/4in. 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. 1/2in. & 3/4in. BSP 25 mm 27 mm nuts 29 mm ribbed 32 mm nuts. Complete with 3/8in. Cordless drill adaptor, 1/2in. Square Drive; Extension tube & full instructions.