Discovery make their scope tubes out of a single piece of aluminium making then strong and light. All internal parts are built to last – and are tested to withstand impacts so will withstand recoil for the most brutal rounds. All Discovery scope tubes are O ring sealed to prevent moisture entering the tube – even if submerged in water. The tubes are Nitrogen purged to give a lifetime of fogging and internal moisture protection. Lenses are Fully Green Mult-coated to give increased optical performance and colour contrast.