Viair makes a top notch compressor but their tire inflator guns are junk. I bought one of their guns (and hose) and besides being lousy quality, it leaked out of the box so returned it. Wasn't impressed with the curly hose either and it went back too.
The 300P and up models have the design set up so the hose/compressor won't stay pressurized (in some models) when the hose is disconnected and the quick connect fitting at the compressor is a male type, the reverse of "normal" compressors. They also use a goofy kind of fitting on one end of the hose too.
The inflator guns can only be used if you have a tank or automatic compressor model with built-in pressure switch so are talking about a Viair pistol grip inflator gun like in 2nd pic? Or maybe a lower & slower rated models with locking style chuck like the 84P (as in last pic)? The 3rd pic is a cheapo, dime a dozen, inflator gun on ebay for under $10 (incl. shipping). Notice how similar they look. Viair does not list the accuracy of their gauge either. A good quality inflator gun with digital gauge like a Longacre, Joes Racing, Snapon, Intercomp, etc. are in the $100 - $400 range!
I really wanted a pistol grip style gun at first but eventually gave up looking after seeing the prices. I have a 300P model Viair compressor and installed a Viair pressure switch inside the end cover, a gauge and a female quick connect fitting to make it automatic. Ends up being basically a 450P model. Then I bought a super-flexible 1/4" poly hose and added a male fitting, a standard tire chuck and thumb operated pressure release valve. The valve is needed to release air pressure so the comp. doesn't get stored away with the head pressurized. Then I just use an ordinary handheld digital pressure gauge. Can't remember numbers for sure, but I tested inflating a tire from 60-80 psi and it took a couple of minutes or so. Not bad IMO for RV-ing use.
Viair now has performance data on their site and their CFM ratings are at zero psi, unlike a regular 120 volt compressor which have a CFM rating at 90 psi. If inflating LT tires for ex. to 80 psi, the 300P or 450P Viair models only do 1 CFM, down from the 2.30 (300P) & 1.80 (450P) ratings. Plus, some models have a 33% duty cycle and some are 100% so some models can take 3 times longer to inflate a tire.
You could also get a locking style chuck, check valve, thumb-operated valve and gauge and makeup your own functional equivalent to an inflator gun.
Having said all the above, for bicycle tires, get an old-fashioned foot pump! Faster and cheaper... :)
