Forward Controls Design Nautilus Variable Timing System takes the frustration out of timing your muzzle brakes, flash hiders, and other muzzle devices. The NVTS features a unique two-part system with a base and a disc with an interfacing layered shelf system. These 'shelves' allow the Nautilus Variable Timing System to be dialed in for up to 330-degrees of rotation for the muzzle device, allowing for precise timing without having to sort through a pile of shims to get the desired result. Precision machined from 4140 chrome-moly steel and finished with a durable QPQ nitriding process to protect against corrosion, the Forward Controls Design NVTS is a durable and ingenious solution for timing muzzle devices.Features: Ingenious 2-part design 4140 CMV Steel construction CNC-machined for precision Up to 330-degrees of adjustment For 1/2x28 TPI barrel threads