Actually Jeff only advertises the protection at 5 mph, not 20. I'm not sure what those numbers mean though. Maybe up to 5 mph the bumper will absorb all of the impact without damage to either the SuperBumper or the vehicle & up to 20 mph the SuperBumper is sacrificial but the vehicle sustains little or no damage.

Going wider on the SuperBumper is probably a no-go because the further away from center the impact is, then the more torque applied to the receiver bar (what KAT refers to as the 'stinger'). Basically the stinger would bend rather than slide into the receiver.

Below is a pic that Jeff used to have on his website showing the result of a solid hit on the bumper. IIRC pic was submitted by a customer after an accident (not me though).