He didn’t give a current rating. “mAh” measures energy storage, and 3100mAh is enough to jump a car a couple times.

Jumping a car doesn’t take a lot of energy. But it does take a lot of power (and therefore current). Small Li-ion car jumpers can be surprisingly capable.

I jumped a stranger’s car with my 66.6 Wh battery the other day. DC output 12V/10A. Peak current 2000A. Battery is still ¾+ full. Haven’t tried charging a phone from it though.

I have actually used this thing several times to jump a car. It works great.