"Around his neck was a crude collar. On closer inspection, I saw it had been made from a piece of check-line leather."
The phrase in bold is quite difficult to understand. If a 'check-line' or 'check rein' is a part of horse harness, how can one 'on closer inspection' judge that the collar is made of this part? Or may be there are experts who can tell the difference between ordinary leather and the-special-check-line leather?
Thanks for any help.