The BPI Advanced Computer Gradient IV is the most technologically advanced gradient system. The instrument has a solid state control center separate from the gradient head. The motor drives the lens holder by means of a long screw for continuous motion. Four programs enable you to easily control the type of gradient. The BPI Advanced Computer Gradient III has a low maintenance powder coated finish. It is constructed from UL listed components (USA Underwriters Laboratory) and meets or exceeds the European CE standards and has a one year warranty.