I second Gilligan's suggestion. I like the same ones with the indicators that turn colors as they absorb moisture. When I used the Moisture Munchers, I used twice as many as needed because I had no clue when they were saturated, so I changed them often just in case.
Moisture Munchers do come in small plastic vials with the blue-to-pink indicators, but they can't be renewed (mine always melted no matter how low the heat and slow the time) and honestly, every package I've ever seen is already turning colors.