The Raptors Airsoft RTQ Steel Enhanced Tight Bore Inner Barrel is a precision-machined upgrade component that can help improve the accuracy and performance of your airsoft gun. It is made from high-quality steel and features a square-cut design with a 6.02mm inner diameter that provides tighter groupings and improved accuracy. This inner barrel is compatible with ICS SIG 552 airsoft guns and it can help increase your gun's velocity, range, and overall performance.