This GLOCK 17 Gen 5 full blowback is up to date in more ways than just one. Not only is this 17 fitted with Gen 5 GLOCK features, but it is also readily equipped with GLOCK's MOS (Modular Optic System) optic mounting solution. Powered by green gas and compatible with existing GBB magazine SKU numbers (GBB) 2276347 and (CO2) 2276348. With full blowback operation, this GBB launches .20 gram BBs at 300 FPS and has an ambi slide stop, and a reversible mag release. With MOS optic plate kit SKU number 2211388, you can mount the micro pistol optic of your choice to the slide of this GLOCK 17 Gen 5 MOS.