"Barry S." wrote in message
...
I was in Harbor Freight today and they were having some sort of huge
sale as it the line was so long I refused to stand in it. But they
had a couple of displays of quick couplers for air tools. I grabbed
a male and female and tried to stick them together. Wouldn't go.
Noticed they had a couple of different sized on the male side, but the
female side of the connection appeared to be the same size.

How does this work? I thought there was only one size for quick
connects. Are their multiple sizes and are some compatible with each
other?

Go to http://www.mcmaster.com and bring up page 230.

1/4" "Industrial" is the generic size and style you find at HF, home depot
etc. most common for construction trades and homeowner tools. Lot of
construction folks also use the 3/8" size, looks the same just larger.
Also comes in 1/2" and larger.

"Automotive" / ARO is the other common style that looks similar but does not
interchange. Also comes in different sizes.

There's a bunch more used for air lines, but you're unlikely to find them at
mass-market retail.

One reason for the different styles is to segregate air sources and
equipment e.g. clean dry air, oiled air, breathing air et. al. as the
consequences of a mix-up could be quite high.