Has been produced in the 60s due to the 151 BCD. Internal storage code: 0500. Square taper ISO interface. 151 BCD modified to also use 144 BCD chainrings. The BCD has been modified from 151 to 144, you can still use both standards. If you don’t find some details you are interested in, feel free to ask. Allowed in 15 days buyers pay for the return.