The 3VA9771-0JJ44: This is a panel-mount accessory, not a standalone breaker — it bolts onto the line or load side of the breaker to handle heavy parallel feeds. If you're wiring a 600–750 kcmil run into a 3VA58 or 3VA68, this is the terminal kit that makes the connection.
What the torque and strip length mean on the bench
It accepts both copper and aluminum stranded cable in the same 600–750 kcmil range, so you don't need a different lug for AL feeders. No control-wire tap on this version — it's a straight power lug, no auxiliary terminal.