The Vortex Cantilever 30mm Ring Mount provides extra rail room for rear Back Up Iron Sights (BUIS) on the Vortex Strikefire II Red Dot
or the Vortex VMX-3T Red Dot Magnifier
. The 30mm cantilever ring will move the red dot forward about one inch. This mount will will work with most 30mm red dot sights.
Model #CM-304 provides lower 1/3 co-witness mounting height of 40mm
Model #CM-305 provides lower 1/3 co-witness mounting height of 37mm