Features and Benefits: 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).