I would never trust a jack while I go underneath the vehicle. Especially a pneumatic one. It could fall as fast as gravity.That said, the results are impressive. Very quick lift of a 7,700 lbs. truck and it weighs less than my other jacks that can't lift it. Easy up and down controls that easily do slow up and down too.My only issue is, the air hose can kink easily and then the jack stops working until you notice.