For BOSCH® system Narrow Wide chainring.

MATERIAL : Cr-mo steel (ASM 4140) heat treated
SPEC : TRSK-BSH-NW = 0 Offset
           TRSK-BSH-NWOF3 = Offset 3mm for OLD 142mm
           TRSK-BSH-NWOF6 = Offset 6mm for OLD 148mm
TEETH : 14T, 16T, 18T, 20T
OPTION : N.E.N finish / ED / BK