This one from Eastwood claims 500 amps. Probably a function of how big the bolt is.
https://www.eastwood.com/4-magnetic-welding-ground-clamp.html?gclid=CjwKCAjw092IBhAwEiwAxR1lRmYD7JzQIa67I_srFf-necFjr3AfhuuHfNczDikJHayTZiKLIeX1ORoCP-wQAvD_BwE&wickedid=491598523414&wickedsource=google&wv=3.1
I haven't gotten that far yet. Got an inverter stick machine that has a switch for TIG. Haven't gotten around to getting argon or a regulator though. I figure it would be a little difficult for me.
I have an inverter stick machine that only weighs about 15 or 20 pounds. That's the real reason I won't bother with the flux core. If I need more heat or have to go outside, the stick machine is easier to deal with. Plus stick electrodes are more cost efficient. Only $15 or so for 5 pounds of 6011.