Shorty Style Regulator This reg is 3.5" tall Maximum input pressure limit is 900psi. For markers that operate under 200psi, best results are achieved from a low pressure output tank. Unit is shipped with adjustment screw turned completely clockwise and reg is in the off position. Turn adjustment screw counter clockwise to increase pressure and clockwise to decrease pressure. For best results, shoot your marker while turning set screw in small increments.