S3 Star Head compression insert with very high compression for the KTM EXC, Husqvarna TE, Sherco SE (2016 and newer), and Beta RR enduro motorcycles. This insert is meant to be used at high altitudes to improve compression when there is little air and will give your bike that extra power boost. Uses the best alloys available to obtain a better power output and improved traction. The advantage of these heads is that they can hold more water and have thicker walls which helps with the cooling rate thus improving low revs power. Insert fits with S3 Star Heads and also provides increased cooling capacity.