The Sd.Kfz.251/21 was an anti-air and ground-support version of the Sd.Kfz.251 half-track built for the Wehrmacht in late World War II. The vehicle featured a single turret with triple 15 mm MG151 autocannons as its main armament. It was frequently deployed in platoons of six to maximise coverage, though it suffered from high ammunition consumption that allowed for only 90 seconds of continuous fire. In total, 387 vehicles were built.

Introduced in Update 2.3 "Hot Tracks", the Sd.Kfz.251/21 is effective in its intended role as an SPAA thanks to its armament: three 15 mm autocannons with a high rate of fire, offering enough stopping power against most planes it will face. Due to its half-track configuration, the vehicle has good off-road mobility, allowing it to reposition quickly. The main downsides, as with other SPAAs, are its weak armour protection and long reload time, which may leave it vulnerable to strafing aircraft.