Convertible from external to internal pull - all except 87006 make 2 pullers. Self-locking jaws hold puller in place for one-hand operation Interchangeable parts allow tremendous variety of applications. Jaws are forged for maximum strength and durability. All pullers are easily assembled without the use of other tools. Curved anvil heads on the pressure screw allow use of hammer to shock frozen gears and pulleys, Pullers are compatible with slide hammer sets 87016, 87017, and 87018, simply match the correct pressure screw size.