Facebook. No idea...

[rwm]

 

[woodchucker]

i'm betting a weld positioner for on the go.

 

[MrWhoopee]

That ad is just selling chucks, I've seen them with a super-spacer, but when you click on the link it takes you to a listing for import chucks.

However, image search reveals that the picture is a device called a "roll-out wheel", used in pipe welding. I'm guessing it is a manual rotary positioner.

Roll Out Wheels For Pipe Welders | Basic, Pro, & DIY Options

Our roll out wheels are designed to make your pipe welding projects easier. Save time and money by using the right tool for the job. Most orders ship same day.

hkfabrication.com

 

[NCjeeper]

I would hate to hit my shin on that.

 

[woodchucker]

I would hate to hit my shin on that.

You wouldn't have a shin, a leg, a thigh after hitting that.