[Longhorn Man]

a traditional bumper jack can shoot out when the car rolls forward. When this happens, it can take out whatever, or whomever is standing right behind it. The typical mistake was doing it on even the slightest of hills with no chock block. Lifting the rear of a rear wheel drive was the most common for disaster.

While a bottle or sizzor will topple easily, it isn't as sensitive as a bumper jack since the point of contact is lower and is more stable. The bumpers of cars made after 73 had the bumper 'shoks' in there and would move around when jacking, the frame only goes up and doesn't wiggle. Plis when the tire rolls one inch, the frame only goes one inch, yet the bumper will move a tick further causing more of a lean on the bumper jack.

The red one seen above is a common piece for 4 wheel drive trucks with lifted suspention and/or oversized tires. Since most bottle/sizzor jacks won't lift high enough, and a traditional factory bumper style jack would be very unsafe, this is one answer to roadside emergencys. (a floor jack is about the only other answer) I always thought those red ones (sky jack is one brand I think) had a real large foot/base to help with stability.

As with most anything, knowing what you are doing is the best way to avoid disaster with ANY jack, be it a sizzor, bottle, bumper, or even a large floor jack. They are all great tools when used properly. Yet, they can all kill you if used wrong.