I had 2 old portable air compressors that broke after 20 years of use. When I replaced them the new ones just bolted onto the tire bars and I felt uncomfortable using them! These 2 chucks with hoses attached screw right into my portable compressor hoses and extend my hose, also I now have a chuck that is more secure than a screw on a compressor hose. These cartridges are easier to use than the ones on my old compressors. I keep a portable compressor in the trunk of both my cars so I'm ready when my tires need pumping. No more waiting for AAA! :)