Bolts not included. 8 and 7 speed compatible. Replacement chainring bolts. Single ring bolts alllow conversion of double ring into a single. Chain pulley slides side to side.
Tube clamp is adjustable to adapt to different chainstays diameters and profiles.
Alloy U clamp that holds the pulley can also rotate for better chain alignment adjustment. 54 and 42T rings are alloy with a steel 34T inner ring. 38T timing rings. About 35mm outside dia, 25mm wide, tapered groove 10mm, 5mm deep. Cartridge bearings on both sides.