Power tank rollbar mounts

Brand new Power tank large rollbar mounts in red, fits round tube from 2&1/8, 1/4, 3/8 & 1/2". Brand new are $69, I'm asking $45 shipped

 

How do these work? Obviously they bolt around rollback (or tube bedrack) and then what? Do they act as a point to bolt a mount on to?

 

They clamp around round tube and then the Power tank bracket (for holding the tank) attaches to the rollbar mounts

 

I'll post up a picture after I get off work so you have a better idea of how they are used

 

So these are meant to go on your round bar, and then the power tank bracket mounts to them.

 

Can someone tell me what a power tank is

 

Its a co2 tank to fill tires and run air tools.

 

Gotcha. Thanks.