Weld-on adapter with 19mm hose connection Aluminium Alu adapter for welding on Hose nipple for welding on Treadstone/s high performance oil and water fittings are machined from 6061 T6 aircraft grade aluminium on CNC lathes. Our fittings have superior strength and are easy and quick to assemble. Viton high quality O-rings provide a durable and leak proof seal, even when using racingfuel and oil. And finally, our black anodizing adds a touch of class and quality that our customers expect from Treadstone Performance.