I have turned a few of the toothpick holder kits and found out the cap will unscrew in your pocket over time. I found a remedy by putting a 3/8" o-ring on and then putting the cap on, it will not unscrew. Just a little note.
It isn't a washer, but a small o-ring. On the larger pill holder there is an o-ring included. I also tried the o-ring and it works well and the edge of the little cap hides it.