The Outers unit, designed for .22rf. It is made out of 10 gauge or heavier steel, and will handle magnum class airguns with ease. What I do is fasten a piece of heavy cardboard across the entire front opening, using duct tape all around the outer edges - effectively "sealing" the trap. The cardboard face provides a surface to tape the targets to, and most importanly, contains the lead dust and pellet splatter. Every so often, remove the tattered cardboard, empty the trap directly into a plastic trash bag, and reapply the new cardboard facing. The cardboard also tends to muffle the sound of the pellets hitting the steel a bit, but if you want it real quiet, fold up some old rags and tape them across the back of the steel backing plate.