Hi.I have a Lee Filter System. I have 2 100mm ND Polyester Filters + Lee Filter mounts.ND 0.6ND 0.9Lee 100mm Polyester Filter MountsWhat I don't understand is how the filters mount into the frames. The frames are exactly 100mm x 100mm and the filters are exactly 100mm x 100mm, so the little nubs which snap to hold the frame together are overlapped by the filter. How are you supposed to snap the frame together with the filter in it? Are you supposed to cut the filters? puncture the filter? I am really confused.How do people here use the polyester filters with the Lee filter holder?thanks