I have these but have never used them or set them yet.. I need to get on that.I went with Stuan. I've seen the struggles folks in my club have had with the off-brands and the ARB setup that removes the valve core... they all went with Stuan after several trips.
I have this same compressor, love it...Haven't used it to deflate yet.The inflator gun thing with the pressure gauge on my Viar 450p compressor has a little button that deflates. Its maybe not as quick as those screw on deals, but you can use it without the air hose connected, so that is what I have used before. I like the gauge.