Manual pressure release for maintaining peak readings. Professional grade threaded adapters for leak proof seals. Extended hoses for hard to reach applications. Large, easy to read 2-3/4" diameter gauge. Adapters to fit engines as small as lawn mowers, chain saws and trimmers Quick disconnect coupler for easy accessory changes. This comprehensive kit includes everything required to perform dry and wet engine cylinder compression tests commonly used to detect ring or cylinder head problems, sticking valves, blow head gaskets, and more. Includes adapters for use on motorcycles, marine and small engines, and an air-hold adapter for performing valve seal repairs with removing the cylinder head(s). Not for use on diesel engines.