●Includes 1 PVC rubber reducer (please make the selection on size and color) and 2 hose clamps ●Connects intake pipes with corresponding sizes inlet. Measure the outer diameter of the pipes you are trying to connect with the couplers. ●For Example the pipes you are trying to connect are 3" and 2.5" in OUTER DIAMETER then you will need to purchase a 2.5" to 3" coupler as size then choose the color. ●Not recommended for turbo or supercharger piping connections ●Note: Color contrasts of the Red/Blue/Black varies depends on the size. For examples, some red couplers come with a bright red or dark red or regular red.