having disassembled for cleaning a number of bikes recently, and having failed to tag their various chains adequately, I know find myself with about 6+ chains, which while used used are all showing less than discard stretch readings.

rather than drop $15, $30, $45 on replacement 6. 9 or 10-speed chains, I would like to reinstall these used chains.

How though can I determine which are for 8-, 9- or 10-speed systems?
width at the widest point? roller width? is there usually any code marked on the links themselves?

thanks

Peter