When sourcing fireworks mortars, the material choice is paramount for safety. High-Density Polyethylene (HDPE) is the industry standard because it is shatter-proof; if a shell explodes inside, the tube will tear rather than fragment into dangerous shrapnel. For professional displays, Fiberglass (GRP) is also common due to its lightweight nature and high heat resistance, though it has a shorter lifespan than HDPE. Avoid low-grade PVC, as it can become brittle and create lethal shards upon failure.