a rip drive is a pole with a "wheel" attached at the end, this pole is connected to the drive internals of the loader.
if the battery in the loader fails mid-game, it allows you to carry on firing, slower maybe cos you have to keep turning the wheel in order for the balls to make the breech, usually allows 5-10 balls at a time. it becomes a pain but it is a life saver and keeps you active and crucial on the field.
it also means if the loader jams then you can clear the jam by turning it forward and backwards to clear the jam (usually a quick shake suffices but sometimes not.
id buy it.