Compress springs on overhead-valve engines to remove or install the valve keepers. Use this lever-action spring compressor to easily dismantle and reassembling cylinder heads. Adjustable jaws cup the valve spring retainer, while a swiveling plate screw holds the valve closed. Nickel plated carbon-steel construction for strength, durability, and corrosion resistance. Jaw Open Min. 7.62 to 16.51cm (3 to 6-1/2 in.) Open Max. 14.29 to 23.5cm (5- 5/8 to 9-1/4 in.). Throat Depth 14.92cm (5-7/8 in.).