Quality reproduction piston made by Lil Red Barn. Compatible with Hilti cutoff saws. The saw came fully assembled, and even included a consumable kit (2 Main Filters; Fuel Filter; Spark Plug; 5 Starter Ropes). Hilt took an already awesome gas saw and made it even better. The choke is removed and replaced with an "Easy Start" automatic choke system for more first-pull starts. Air that flows through the air filter is first pre-cleaned using centrifugal force, separating dust and debris before it ever gets to the filter. Meaning less filter changes and more work time. Changing the pull rope or air filter can all be done quickly and easily on the job site. Strong steel springs help eliminate vibration. This gas saw performs well in a variety of base materials including all types of concrete, masonry (hollow-brick, limestone, etc.), steel and asphalt. The saw starts easily, has plenty of power, balances well and vibration is kept to a minimum. Using this tool is a real pleasure. Highly recommended!