This is a very intriguing device that uses a low current at low voltage to transfer moisture from inside an enclosure to the outside.  Effectively a solid state dehumidifier with no moving parts.
The version I put in the box is a PD2 and is rated to remove up to 84mg of water a day, so really intended for small enclosures.
The large square unit can handle up to 2.9g of water a day.
Note that these units are intended for use with sealed electrical enclosures and not for house dehumidification.

When I mentioned a ceramic capacitor in the power supply I actually meant the ceramic HRC style fuse which is a good design choice.

The test results in the small test enclosure were:-
9.30pm 67%  peaking at about 200mA then settling at 86mA.
10.00pm 58% 25mA
10.30pm 49% 24mA
11.00pm 44% 23mA
12.20am 41% 21mA
1am 37% 21mA
3am 33% 20mA
Running the unit for about 12 hours the following day bottomed out at 22% at 17mA.

The modules I showed here were generously contributed by Westside International when I enquired about getting…

A dry box is a storage container in which the interior is kept at a low level of humidity. It may be as simple as an airtight and watertight enclosure, or it may use active means to remove water vapor from the air trapped inside.