The Lonex reinforced hop up is built using aluminum alloy. The design of this product improves the air seal and the ability to absorb shock. In addition, the interior of the Lonex Hop Up Unit is polished to increase the speed and reduce the amount of friction of the BB as it travels inside the hop-up. With the included parts, this hop up is an easy way to increase the performance of your airsoft gun. Some assembly is required in order for the hop up unit to be functional.