The Echo P021038790 Piston Kit helps restore proper compression and internal engine movement for reliable equipment operation. This replacement piston kit is designed for compatible engines and works inside the cylinder, moving up and down as part of the combustion cycle to transfer force to the crankshaft. Proper piston movement supports efficient combustion, power delivery, and over... https://www.wholetoolbox.com/echo-p021038790-piston-kit/P021038790.html