Many types of high explosives are rather insensitive to a detonator.

To make them detonate reliably, a booster or primer charge is placed between the detonator and the main charge the added “punch” offered by the booster charge ensure reliable “high order’ detonation of the main explosive charge.

In prior British military technical parlance, a booster cup was called a “GAINE” when used in the firing trains of ordnance items.

Securesearch Inc., manufactures a wide range of simulated cast TNT boosters and slip-on simulated PETN rubber-bonded boosters in several sizes and colors, for both classroom awareness training and x-ray training.