Typically, two or more rows of slat are attached to the conveyor chain. These conveyor chains are used mainly to transport the body of the car, for car assembly, test lines, showers, etc. Two types of rollers are available; center mounted (F-roller) type, and side rollers. Water-resistant coating and special material selection are possible in accordance with the working environments. In particular, by mounting bearings to the F- roller, or by selecting special plastic, the surging phenomenon can be prevented, and noise and the overall weight are reduced.