The Thyrm CellVault, CellVault XL, and CellVault-18 are waterproof, attachable gear solutions. They were designed for battery storage, but can store many things in their food-safe plastic, including survival gear and medicine.
The CellVault comes in two sizes:
CellVault is the original size, designed specifically for CR123s, though it also fits AAA and AA alkaline batteries well.
CellVault XL is twice the original size, giving a lot more storage options for CR123s, AAAs, and AAs, but also fits two 18650s.
CellVault-18 was designed specifically to fit rechargeable 18650s and 18350s, as well as smaller batteries.