Smart Parts SP-8, an electro-pneumatic paintball marker manufactured by Smart Parts
They include, for example, the Tippmann X7 and the U.S. Army developed Alpha Black (which resemble an M16), RAP4's T68 Paintball Markers (Which resemble the M4 Carbine, has an internal Air or CO2 tank and is magazine fed), or Smart Parts SP8 (based upon the German Heckler and Koch Prototype XM8, and much of the Armotech product line).