The truvativ aluminium 104 bcd chainring a 36 tooth 4 bolt mtb bike chainring made of aluminium a super tough and long lasting inner chainring 3 mm thick chainring 104 mm bolt circle diameter bcd good quality long lasting ring available in blast black colour truvativ aluminium 104 bcd chainring features 4 bolt chainring made of aluminium 36 tooth for 104 mm bolt circle diameter bcd a super tough and long lasting inner chainring