SHS is one of the leading manufacturers in the airsoft industry when it comes to performance upgrade or repair parts. SHS Airsoft offers you reliability and quality at an affordable price. After 4 years of development, SHS Airsoft products have been sold to over 30 different countries and continues to expand. The SHS Full Metal Tooth Piston is fiber reinforced for extra durability under strain inside the gearbox. The full metal teeth rack is ideal for high speed, high velocity and stock setups. Overall, this is an exceptional product and worthy upgrade for the price.