Numbers booster, calendar filler, streak aid, etc. Caches are in film cans hidden in the usual ways but, you may come up on a few different ones to add a little variety. Log only so BYOP. On select caches you will find a Letter = # (Example B=3). Collect these through the series and they will lead to you a bonus cache at the end! Happy Hunting!
Shout out to Nomad721 on the FTF!