Manufacturer: SHS For M4A1 and M16A2 (M4/M16) AEGs Material: Aluminum Has Internal O-ring The SHS Aluminum Air Nozzle is a high-end upgrade part that increases air compression by minimizing the air leakage caused by standard stock air nozzles. SHS has manufactured these air nozzles with an internal O-ring that provides the best seal between nozzle and cylinder head. Stock air nozzles are often made from plastic and wear out with use. The robust high-grade aluminum used to manufacture these air nozzles means that they are built to last. Professional installation of this product is highly recommended. Airsoft Station offers installation of most parts by professional airsmith technicians. For inquiries regarding installation of replacement and upgrade parts as well as other airsoft services please contact the Airsoft Station Tech Department here.