The Zipper shoots a ball of energy that sticks to the ground upon impact, repeatedly going the same distance to the right and the left of where you hit, dealing 4 damage every time it touches an enemy. The Zipper will always deal the same amount of damage no matter if the enemy stands to the left, to the right or directly where you hit. Visually the weapon indicates that a perfect hit would increase damage even though it doesn't. With a puny 32 damage against a single target it is better to wait until multiple enemies are grouped up since a guaranteed 32 damage can be dealt to each target, as long as they are within the range of the left-right path.
Double zipper works just like zipper, but has two energy orbs zipping around on the ground. As expected, two orbs mean half damage, dealing only 2 damage at a time.
Zipper quad has 4 orbs zipping on the ground for quite some time dealing 1 damage each time. Fairly powerful against groups. The yellow zippers travel slightly further than the blue zippers, but not enough to be remotely significant.