Both the Charge Cylinders and the Holder are made of very durable and blast resistant urethane and can be re-used indefinitely. The Charge Cylinders are designed to use igniters and up to 2.5 grams of FFFF black powder. The Charge Cylinder snaps securely into the Holder. The powder is then held in place with a bit of wadding and a vinyl cap. The set includes 2 x Charge Cylinders and Holders and 4 x vinyl caps.