Rubber push-lock hose with a 1/2 inch, 12.7mm internal bore. It is made to be used with push-on barbed hose ends, which are simply pushed into the hose bore where the barb profile grips and holds without any clamp or crimping tool. The 12.7mm bore suits oil cooler plumbing, larger fuel supply and return runs, coolant lines and breathers on low-pressure circuits. Assembly lube makes fitting the barb much easier on this size. It cannot be used with PTFE, nylon braided or stainless braided hose ends, which need entirely different fittings, and a clamp is worth adding on any line carrying meaningful pressure.