C02 Half Blowback - extremely efficient due to the fact that there is less slide travel and it uses the left-over air from firing the bb to cycle the slide. 

The design is way less complicated than a full blowback design. 

Manufacturing costs are lower than a full blowback, which brings down the retail around 30-40%.

Features

Lightweight, rugged injection molded polymer frame w/ aluminum alloy slide; Fully licensed by GLOCK w/ complete rollmarks on the slide and logos molded to the frame
Traditional GLOCK sights
Functional GLOCK trigger safety
GLOCK Gen4 style frame with finger grooves removed
Slip resistant grip texturing w/ front & backstrap checkering
Ambidextrous slide stop
GLOCK accessory rail
Realistic gas blowback system to simulate slide cycle and recoil