Shield is able to take strict precautions against dust and chips, hard sand, into orbit, to reduce the damage of the hard granular foreign objects on the surface of the sliding rail, rail handling can reduce the deformation of the machining accuracy, and maintain the machining accuracy 
 Rectangular shield is the most common monitoring system shields, low cost, rugged, varied size, style, beauty. Indoor rectangular shield does not require special anti-rust treatment, usually painted or anodized aluminum, steel or high impact plastic such as polyvinyl chloride (PVC), engineering plastics (ABS) or polycarbonate (such as of Lexan) and other materials. Rectangular shield open structure of the roof removable front and rear cover open-type, slide out of style, roof strut-type hinges suspended, roof sliding, a variety of structural way to install, repair , easy to maintain for the purpose.