Model 501(601) is entirely straight in layout. Model 501-R(601-R) is identical to Model 501(601) except that No. 5001-A(BL)neoprene-tired Ball-Bearing Single Carriers are used in place of the standard nylon-tired No. 5001(BL) single carriers. 

These track is also available with black finish at additional cost (601 series and 601-R series).