These cartridges fit the Tap-a-Draft Tap we sell. They also fit the 1 liter seltzer bottle that we sell and most modern seltzer bottles sold today. They are not threaded. The 8 gram cartridges are also available in boxes of 24, or you can purchase them individually. The cartridges are 2.5 inches long and 3/4 inches in diameter(accurate to 1/8 inch. Constructed of steel, gas cartridges can be recycled where scrap metal is accepted for recycling. **NOTE: We can only ship these cartridges by UPS Ground. The US Postal Service considers them a hazardous material.