It's a pill holder. Most likely waterproof. It usually has a small metal o-ring through that top hole that can attach to a keychain. It's for people who have medicine like nitro pills that they need to carry for emergencies.
Here is one on Amazon.
Side note: I use these on my keychains, but I keep folded money in there. For emergencies.
This is what I got on Amazon they're perfect and nice and small.
I’ve only been taking meds for a couple months (lamictal and latuda) and I’ve already missed two doses (not in a row) but GOD that crash is something else. For some reason I didn’t think it’d effect me? It was crazy how drastic my mood shifted I went from feeling ok to being immobile-so scary. Anyways the second time was enough for me to order these babies that very day 10 Pcs Portable Pill Case,... https://www.amazon.com/dp/B07BF3R938?ref=ppx_pop_mob_ap_share theyre portable pill cases and you can attach them to your keys, that way you NEVER have to go through that again, I really hope this helps, and I hope you’re doing much better!
Get a travel case like this one that you can keep on your Keychain and cut the pills in advance :) that's what I do.
I just bought a pack of 10 bison tubes on amazon for $9.
https://www.amazon.com/gp/product/B07BF3R938/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I ordered all of these on Amazon.
Bison Tubes https://www.amazon.com/dp/B07BF3R938/ref=cm_sw_r_apa_i_XSnUEbHGG2NNS
Polypropylene Tubes https://www.amazon.com/dp/B074CX1GQ4/ref=cm_sw_r_apa_i_xTnUEb37Q5RA7
I got 'em $15 for five, but still pricy.
I put 2 or 3 into a pill case and good for a full day out and about.
10 Pcs Portable Pill Case,... https://www.amazon.com/dp/B07BF3R938?ref=ppx_pop_mob_ap_share