Splits frozen or rusted nuts without damage to the bolt. It is conveniently sized to work in hard to reach places. Made of the finest steel, heat-treated and forged for long service. To operate, just use a regular hand wrench and turn the power screw which has a hydraulic pump built inside multiplying the power exerted upon it. A set is composed of two models: No. 316 size up to 1/2″ BSW (Across Flat 20 mm), No. 336 size up to 7/8″ BSW (Across Flat 33 mm), Sold in sets only.