The VAC D400 is a microprocessor based, “intelligent” instrument that can be mounted to rotary or linear pneumatic actuators for accurate positioner control. This BLX positioner unit, while sophisticated in its accuracy and performance, is simple to mount, calibrate, and with good filtered air and proper maintenance, can provide very accurate and trouble-free service for many years. BLX Valve Accessories and Controls is an Independent manufacturer of Valve Accessories and Controls for the process industry. Their product package consists of valve positioners, position indicating switches and rack and pinion actuators.