I have a custom air compressor with a pretty decent manifold running through my garage, but its always used 1/4in couplers even though I use 3/8ths in hoses and regulators. I always wanted to go 1/2in for my sand blaster and air tools but the couplers are hard to find and expensive.
So today I found "ColorFit by Milton HIGHFLOWPRO Coupler & Plug Kit - (V-Style, Purple) - 1/4" NPT, (7-Piece)" $15 is enough to convert 1 hose and some tools. Milton color codes their fittings/couplers as to size. The purple V hi flow sizes are somewhat compatible with 'standard' 1/4in... but since there are like 3 or 4 fitting types (Industrial, Automotive, Asian, 'combo' etc) I like that I can see the color and know that's my high flow hose.
Its a 1/4in NPT coupler with a huge friggen oriface. Says it can push 75+CFM vs the much smaller standard 1/4in orifice.
Standard 1/4in fitting/coupler on the left, the Milton HIFLOW V fitting/coupler on the right.
Some cool videos:
https://www.youtube.com/watch?v=Mqbk7BnsLbc
Amazon lists the starter kit for $15
https://www.amazon.com/ColorFit-Milton- ... IGHFLOWPRO
Home Depot also sells them:
https://www.homedepot.com/p/Milton-Indu ... /303500129