Extremely durable with high build quality * Ready to use right out of the box * Should fit in most 8mm Gearbox AEGs * Disclaimer: Any and all airsoft upgrade parts purchased from Airsoft Megastore will be used/installed at owner"s discretion. Actual performance results depend on quality of installation and other possible performance-affecting factors. We are not responsible for any damage that may occur with improper installation. For best results, please do all upgrades at a certified professional airsoft technician/shop.