SPG / SPH
Self Propelled Guns and Self Propelled Howitzers.
A howitzer is a type of artillery characterized by a relatively short barrel (barrel length 15 to 25 times the caliber of the gun) and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent. A gun is a type of artillery (characterized by a longer barrel, larger propelling charges, smaller shells, higher velocities, and flatter trajectories). Howitzers and guns are usually organized in groups called batteries.
M107 Self-propelled 175mm gun at Larkhill in 1971
M109 self-propelled 155mm howitzer at Larkhill in 1971
M109A2/A3 Howitzer KZ-88-11 at Maaldrift, The Netherlands.