These lids and liners are to be used with the 3M 2.0 PPS Pressurized Cup System. Kit contains 50 disposable lids with 200-micron filters, 50 disposable liners, 1 reusable hard shell cup with measuring marks and 32 sealing plugs. If you are switching from the old 1.0 system to the new 2.0 system, it will require all three new parts to function; 2.0 Adapter, 2.0 Hard Cup and the 2.0 Liners kit. You may notice a couple of new things in the liners kit. It will come with one hard measuring cup that has measuring marks. It helps take the guessing out and stops wasting product. Just set your liner in the cup and pour to the needed measurement line. Also, the lids now have a collar attached to it. This is because these lids and liners work in both pressurized AND gravity-fed cups. However, for the MAXUM II HVLP spray gun, pressurized is required, so just pop off the ring and then install the liner into the cup just the same as the 1.0 kit was assembled. Its that simple!