Liner size?

We bought a new in box pool from craigslist and it came with a brand new liner. The installer opened the liner a little and he said it is for a 48" pool (wasn't there when he did this or know how he measured). He said it is definetly brand new beaded liner but we had to order one to fit 52" pool. I would like to try to sell this liner on craigslist but don't know the size and installer did not recommend opening it up since we arent' going to use it for fear it might get torn. Is there some way of knowing what size this is without unraveling it? Some code or # on it I can look for?

Thanks!