Sig Sauer PROFORCE M17 AIRSOFT PISTOL BLACK CO2 VERSION ASG Fully automatic semi automatic select fire with Fully automatic semi automatic select fire with 450 rd high capacity magazine The full length optics rail comes standard with flip up removable iron sights and plenty of room to attach additional sights and scopes – Optic Ready Slide with Removable Rear Sight Plate– Pistol Uses Both CO2 or Green Gas Magazines (Alternate Magazines Sold Separately)– Field Strippable with Similar Balance and Weight As the Real M17– Metal Slide Construction with Full Blow back Action– (1) 21rd Metal Magazine– Caliber 6mm Plastic BB– Replica of the US Army M17 Pistol– Up to 410fps (CO2) 320fps (GG)