This pre-separator picks up most of the chips which would otherwise end up in the collector bag. The advantage is that I can wait much longer before emptying the bag – a disagreeable chore. I bought the metal trash can and two 4″ collars from a home improvement store. I then cut two holes in the lid with a rotary cutout tool and installed the collars by bending back the tabs on the inside. To seal them I ran a bead of silicone caulk around each one.