SPEG 06-04 is a model number of 6mm to 4mm O.D tubing stainless steel union tee reducer push in air fittings, T shaped body designed to connect pneumatic tubes of 6mm O.D at both ends and 4mm reducer tube at a 90° angle. It's very easy to push in and pull out the tubes from SS union tee reducer push to connect fittings without tools help.