5 adapters in different sizes for different spring diameters on most cylinder heads. This enables proper mounting of the valve spring and makes the spring compressor easier to use. Heavy-duty steel construction with an oxide coating that resists rust. The surface of each part is smooth to ensure easy operation under high compression. C Clamp jaw design: made from 1.7 mm thick heat-treated steel with a black oxide finish. It is strong and resistant to bending or deformation during compression. The two ends of the C clamp are aligned in a straight standard line to help prevent slipping during use. Easy to use: Close the coil spring compressor until the center bar touches, then insert the compressor into the coil spring. Compress the spring for removal or installation, and release the compression only when the spring is set for installation. Note that compression springs store significant energy and must be handled and decompressed carefully. Safety and handling: Keep hands clear of the spring and use steady, controlled force during compression and decompression to avoid sudden release. Applications and use scenarios: - Automotive engines: valve spring replacement or service on a wide range of cars and light trucks with accessible cylinder heads. - Motorcycles and ATVs: valve spring removal and installation on common motorcycle cylinder heads. - Small engines and lawn equipment: servicing valve springs in lawn mowers, generators, and other small engines. Specifications at a glance: - Adapters: 5 sizes for various spring diameters - Material: steel with oxide coating - Finish: smooth, rust-resistant - C clamp: 1.7 mm thick heat-treated steel with black oxide - Function: supports proper spring mounting and facilitates safe compression and reassembly