Plunger tube

A plunger tube is an internal part found on most non-electric blasters.

Details
A plunger tube works differently in both types of plungers. On a direct plunger, it cases the plunger head, O-ring, plunger rod, and spring, and has a small hole, this hole leads to where the dart is loaded. On a reverse plunger, it acts as an air reservoir, when the blaster is being fired, it releases itself onto the plunger rod.