Precision Reflex 30mm Aimpoint Non Adjustable Ring X-High 1.675in Black. 175in constructed of T6 6061 hard coat black anodized aluminum. Top cap is constructed of steel for maximum holding power is held in place with (4) #6-32 screws. Specifications for Precision Reflex 30mm Aimpoint Non Adjustable Ring: Manufacturer: Precision Reflex Color: Black Finish: Anodized Gun Make: AR Platform Gun Model: AR-15 Gun Type: Rifle Fabric/Material: T6 6061 Aluminum Tube Diameter: 30 mm Red Dot Sights-Footprint: Not Applicable Optic Cut: Aimpoint T1 Length: 1 in Condition: New Package Contents: Precision Reflex 30mm Aimpoint Non Adjustable Ring Precision Reflex 01-0030: 30mm Aimpoint Non Adjustable Ring X-High 1.675in Black