All STI Magazines are measured by overall length. Below is a table that breaks down each of the available magazine lengths and their capacity by caliber.
|Length/Caliber||9mm / .38 Super||.40 S&W / 10mm||.45 ACP|
|120mm (For VIP Length Pistols only)||16 Rounds||14 Rounds||10 Rounds|
|126mm||17 Rounds||15 Rounds||11 Rounds|
|140mm||21 Rounds||18 Rounds||13 Rounds|
|170mm||27 Rounds||23 Rounds||N/A|