Quick-release couplings (G1/8, G1/4, G3/8 and G1/2) have been designed to cater for all those situations where, for plant engineering or safety reasons, the tubing in a plant must be frequently connected or disconnected. Quick release couplings allow these operations to be performed without having to release the pressure and therefore save a considerable amount of time.

The third digit in the code (5 or 8) indicates the orifice and hence the size as well. Models which have the same third digit can be coupled together.