Related to the Chinese Fire Arrow, Bang Fai are made from bamboo bongs. Most contemporary ones, however, are enclosed in pvc piping, making them less dangerous by standardizing their sizes and black-powder charges (which contest rules require be compounded by the rocketeers, themselves). Baking or boiling a bong kills insect eggs that otherwise hatch in dead bamboo and eat it, inside out. Skipping this step may cause the bong to disintegrate and melt the pvc piping. Vines tie long bamboo tails to launching racks. The time it takes for the exhaust to burn through the vines (usually) allows a motor to build up to full thrust; then the tails impart in-flight stability. Ignition comes from a burning fuse or electric match.