Integration means stability. Browning’s Integrated Scope Mount System unitizes the ring and base into a single ultra-rigid unit. Machined from 7000 series aluminum alloy they eliminate alignment problems and the possibility of a loose connection between the base and ring. They are available in .400 Standard height .500 Intermediate height and .600 High height versions to fit your needs. – Machined from 7000 series aluminum for high strength and durability – The integrated design eliminates alignment problems and the possibility of a loose connection between bases and rings – .400 Standard height .500 Intermediate height .600 High height – Important: These fit the AB3 only. They do not fit original A-Bolts or A-Bolt II receivers.