A fuse consisting of high explosive that fires the charge without the assistance of any other detonator. It consists of a high-explosive core of pentaerythritol tetranitrate (PETN) enclosed in tape and wrapped with textile countering yarns. Usually, this fuse is then reinforced or completely enclosed in a strong waterproof plastic outer cover. The finished external diameter is normally about 0.2 in (5 mm). Primacord is the best known brand.