Precision-built SIG ASP pistols and rifles depend on quality ammunition and fuel to perform up to SIG standards. And a higher-quality, cleaner gas in a superior-engineered cylinder can influence the lifetime and performance of any airgun. Investing in SIG premium cylinders is a simple way to ensure longer-lasting, SIG precision performance. Sig Sauer AC-12-40 ASP Pre-Filled CO2 Cylinders Size: 12 grams Qty.: 40 cartridges Fits any standard neck air ports Compact lightweight design Stable, consistent power output