Designed to compress valve springs on overhead valve engines. Includes two valve spring adapters, which fit valve spring retainers up to 1" (25mm) and 1-3/16" (30mm). Unique, direct action compressor lever gives better visibility of valve spring retainers located in difficult access areas Jaw opening (A) of 1-3/8" to 5-5/8" (35mm to 142mm); throat clearance of 5-7/8" (150mm).