Filter clips are made from polypropylene for strength and flexability. Double clips or dual clips are used to support additional inline filters or membranes together. The 2" diameter clips are for standard inline filters (approx 2" diameter) and 2.5" diameter clips are for membrane or high flow inline filters (approx. 2-1/2" diameter). Double clips come in three sizes: 2" x 2", 2.5" x 2", 2.5" x 2.5"
