1/2 in
Zhen Dar QDD12: 1/2" Gas Quick Connect, Disconnect Connector W/ Male Insert Plug
The CAT40 model works without issues in both dry and coolant environments.
Miller Weldcraft 53N61S Nozzle Alumina GL #8 1/2" 10 pack
A nice touch is that BHC Parts includes a small sample of compatible lubricant.
COUPLER QUICK CONNECT MALE SWAGELOK 1/2 316 QTM8 DESO
You will notice the stainless steel edges are deburred for safe handling.
Watts 1/2in Dual Check Valve 9DS-M3 Non-Potable Atmospheric Vent Brass Sweat
What stands out about WAGO is the tool-less wire insertion design.
Ideal 74-027 3/4in EMT & 1/2in Rigid/IMC Conduit Bender with Handle
You will find that BUNN models often come with a commercial-grade water filter system.