If you have ever seen the couplers with a button that needs to be pushed before you can install or remove a tool, that button cuts off the air flow so that it is easy to put the tools on, or safer to take them off.  This new coupler from Astro takes that one step farther.  Instead of just on or off, this coupler has a built-in regulator that allows you to adjust the air flow once the tool is in place.  You need to turn it back off when you are ready to take the tool out.  Most people sell the push button couplers for around $29.  These are only $23, and do more ... BECAUSE IT ITS ALSO UNIVERSAL!  It allows the use of all 3 of the most popular styles to work ... Automotive (single ring), Industrial (double ring), and ARO (triple ring).THIS ITEM IS THE ASTRO UNIVERSAL COUPLER WITH BUILT IN REGULATOR.