if you are not going to access it frequently, I found the one from Harbor Freight to be the correct size for my key chain, but the threads not very good...it just carries a couple of aspirin and ibuprofen and not opened frequently

I searched a couple of years ago for Christmas gifts, and found an offshore unit with a rounded bottom, good threads, and has been used daily for pocket carry... sorry, I don't remember the source, but most likely Amazon