1. Top flat picatinny rails, other three sides key hole cutout
<br />2 .Overall Length: 381mm 
<br />3. Weight : (approx) : 436g/495g/525g/576g/677g/712g/717g
<br />4. Inside Dia 35mm (1.4 inch)
<br />5 .Lower rail style with CNC procedure
<br />6 .One piece style more accurate
<br />7 Upper rail is extended over the barrel nut for a 'no-gap' monolithic look
<br />8 Light weight in precision
<br />9 Easy and quick installation
<br />10. High quality aluminum alloy in durable mil-spec style black matte finish
<br />11.With tools, 2 pcs 3" detachable picatinny rails 
<br />12.Shock proof can be used on real fire caliber 
<br />
<br /> .750 Stell 223 5.56 with roll pin
<br />Diameter: 19mm (0.75 inch)
<br />Length: 25.4mm (1 inch)
<br />Overall height: 37.5mm (1.5 inch)
<br />Weight (net): 41g