Fragola performance systems series 3000 hose ends feature the "cutter" method of hose attachment. The socket draws the hose over the nipple and into the cutter. The seal is formed by the cutter imbedding itself into the end of the hose. If no color is specified, the standard part number is for the regular red and Blue. Use these hose ends with our series 3000 stainless race hose only.