Optical Sight Rail (OSR) This item is designed for those people who want optimum optic accuracy without the need for a built-in rear combat iron sight, but need the other capabilities as found on the #38 Ex/S-Ex Military SWAN® Sleeve. This item can raise and lengthen your flat-top receiver while totally protecting the rifles factory dovetails. The #36's allow super low mounting for bench rest shooting while extending the standard receiver to better accommodate all lengths of optics. Super Extended OSR (Optical Sight Rail). Length 14.0'
