ExRings With Dual Setting of 20-30 MOA 30mm 1.6 Inches High. Barrett ExRings with Pin-Lock technology has a dual setting MOA taper utilizing the scope internal elevation adjustment by aligning the scope for long range shooting. Works on flat or tapered 1913 rails with riflescopes up to a 70mm objective lens. High strength aircraft grade aluminum construction. BORS compatible. 30mm rings 1.6 inches high.