rwh963,
Milton is pretty common for connectors, inflators, blow guns, etc. Milton Type "M" fittings are also pretty common.
Milton® Industries Inc. | Tire Gauges, Inflators & Pneumatic Accessories (miltonindustries.com)
As far as hoses go, you get what you pay for.
I use these on air tools, nailers, staplers mainly. They aleviate the weight and direction pulling of the air hose letting you put the fastener where it needs to be.
air swivel connector - Bing images
CCMoe