Measure the enclosed space you want to protect — a safe, case, cabinet, bin, cabin or locker. Not the room it sits in: a sealed container holds its own air whatever the room is doing.

Based on 1 lb of Sta-Dri per 13.3 cu ft of sealed space. Dry the contents before you seal them — a pack manages the air in a container, it can’t pull water back out of a damp box.