.44 - .50 caliber, yellow,holds 45 grains of powder. Reusable tubes expandable for different size balls; patched or unpatched round balls, conical slugs or minie bullets. Will also work for the calibers in between and under, but will be somewhat loose or rather tight to be fitted into the expandable tube. Tubes are permanently sealed on one end and open at the other. Black powder charge is poured into the tube and a projectile is inserted to hold the charge. You now have a complete load for your black powder gun. Field tested for over four years with more than 200 loadings per tube. Machine wash in a loosely woven container, place in washer wit old jeans at luke warm temperature; air dry. Powder will not stick to the tube. For finest results, shake dry tubes in paper bag with talcum powder after washing. Made of high quality vinyl in USA. Sold in a bag of 50.