Linear motion guide assembly consists of rail, block, balls, retainer, recirculator(reverse unit), sealing gasket and side panel. When the block moves in a linear direction relative to the rail, balls run along four raceway grooves which have been quenched and precisely finished. In the top of the block, balls again pass through the recirculator(reverse unit) into reciprocating hole then into raceway repeatedly. The recirculator(reverse unit) has rubber-sealing gasket on both sides to eliminate dust and keep foreign material away.