Sig Sauer Airguns prefilled CO2 cylinders has a compact, lightweight design and stable power output. This model comes in a pack of 15 and is compatible with 12gr air port.Specifications and Features: Sig Sauer AC-12-15 ASP Pre-Filled CO2 Cylinders Size: 12 grams Qty.: 15 cartridges Fits any standard neck air ports Compact lightweight design Stable, consistent power output