It fits your average shank so if you use a shank for your jockey box it should work.

Yes.

It fits on the back of the beer shank to hold a barb that connects to a beer line.

This fits onto Sanke keg tap fittings. It is used to attach a barb fitting and gasket to Sanke keg taps.

Best tool in the world - this replaces the hex nut for either gas or beer line connected to a Sanke coupler. Makes it so you don’t need a wrench to tighten the hex since it’s a wing nut.