The Sd.Kfz. 251 (Sonderkraftfahrzeug 251) half-track was a World War II German armored personnel carrier designed by the Hanomag company, based on its earlier, unarmored Sd.Kfz. 11 vehicle. The Sd.Kfz. 251 was designed to transport the Panzergrenadier (German mechanized infantry) into battle. Sd.Kfz. 251s were the most widely produced German half-tracks of the war, with at least 15,252 vehicles and variants produced by seven manufacturers. The utility of this vehicle led the German Army to develop the similar looking but shorter and lighter Sd.Kfz. 250 as a supplement.
Some sources state that the Sd.Kfz. 251 was commonly referred to simply as "Hanomags" by both German and Allied soldiers after the manufacturer of the vehicle. German officers referred to them as SPW (Schutzenpanzerwagen, or armored infantry vehicle) in their daily orders and memoirs.
Pionierpanzerwagen (251/7). Another assault engineer vehicle; this had fittings to carry assault bridge ramps on the sides.
Learn more on Wikipedia