Booster is made of a high explosive composition cast into a cardboard/plastic shell. Two longitudinal tunnels in the booster accommodate either a signal tube detonator or detonating cord. One tunnel has straight walls while the other is blocked at the top of the booster to provide a stop for the detonator. Detonating cord or signal tube are protected from damage by a recessed well at the base of the booster.

Cast Boosters have a high density and a high velocity of detonation (VOD) to maximize performance.Cast boosters are reliably initiated by detonators or by detonating cords containing at least 5.0 g/m PETN. These boosters have been specifically designed to provide reliable initiation of pumped, augered and packaged explosives. The main intended application for Cast boosters is for use with ANFO and Bulk explosives.