Below is a picture of barbed membrane plates. They are used with single ply membrane roofing systems such as TPO, PVC and EPDM. These plates are screwed into place with a fastener, into the center whole, on to the top of the membrane through the roof deck to hold the membrane down and in place. The more barbs per plate, the better the bite and hold on the membrane. The single barbed plate (on the left) is used in most installtions. Systems designed for protection from high wind gusts could require the double barbed plate on the right.