The Silent Dry Hypercube is a rechargeable gun safe dehumidifier: a block of nano-porous silicon desiccant in a frame with silicone corner guards and a hygrometer on the front. There is no cord and no hole to drill. When the hygrometer says it is full, you dry it out in the microwave and put it back. It comes in three sizes. Below are the specs for each, how to recharge it, and how to pick the right one for your safe.
Silent Dry Hypercube specs
| Small | Medium | Large | |
|---|---|---|---|
| Size | 122 x 122 x 60 mm | 122 x 122 x 75 mm | 122 x 122 x 88 mm |
| Desiccant | 600 g | 800 g | 1,000 g |
| Water per cycle | 180 ml | 240 ml | 300 ml |
| Silent Dry rating | 600 L | 800 L | 1,000 L |
| Our sizing | Cabinet up to about 150 L | 20 to 30 gun safe, up to about 400 L | Big safe up to about 600 L, or a damp basement |
| Price | $44.88 | $54.88 | $64.88 |
Water per cycle is Silent Dry’s figure at 25°C and 85 percent humidity, and the litre rating is theirs too. Both assume good conditions, so our sizing is more conservative. All three sizes are made in Taiwan and use a patented desiccant (US patent 10549258).
How the Silent Dry Hypercube works
Desiccant pulls water vapour out of the air and holds it in its pores. In a closed safe, the Silent Dry Hypercube brings the humidity down and keeps it there until the block is full. The hygrometer on the face reads the air in the safe, so you know when that happens. Aim for 30 to 50 percent, the range our gun safe humidity guide explains. When the reading climbs past 50 and stays there, it is time to recharge.
Unlike throwaway silica packets, the block doesn’t run out in a few days, and unlike a calcium chloride tub there is no liquid to spill. The corner guards are heat-resistant silicone, so the unit goes in the microwave as it is.
How to recharge a Silent Dry Hypercube
- Take it out of the safe and close the door.
- Microwave it for the time printed on the box for your size. The bigger blocks take longer.
- Let it cool to room temperature on the counter. A warm block absorbs poorly.
- Put it back in the safe with some air around it, not wedged between guns.
How often depends on the safe. In a heated room it can go months. In a damp basement in spring it may be every few weeks. Check it weekly for the first month and you will learn how fast your safe fills it.
Which size do you need?
Work out the inside volume of the safe: height times width times depth in centimetres, divided by 1,000, gives litres. Then:
- Hypercube Small, $44.88: cabinets and small safes up to about 150 litres, or an ammo cabinet.
- Hypercube Medium, $54.88: most 20 to 30 gun safes, up to about 400 litres.
- Hypercube Large, $64.88: big safes up to about 600 litres, fire-rated safes, and anything in a basement or garage.
Two units in a big safe beat one working flat out. For a pistol case or an ammo can, the Invisible stone ($24.99) is the same material in a 5 cm block.
Hypercube or electric rod?
A rod warms the air so water doesn’t condense, but it doesn’t remove any, and it needs an outlet. The Silent Dry Hypercube removes the water and needs nothing. In a very damp basement, use both. The full comparison is in rechargeable vs electric rod, and our gun safe dehumidifier picks cover the other options.
What else goes in the safe
A dehumidifier looks after the air. For the steel itself, put a VaporTack SilentDry in the chamber of the guns you care most about ($24.99 for a 12 gauge two-pack, with rifle and pistol calibres too) and wipe bare metal with the oil pen ($12.49). Take the VaporTack out before you load. Our guide on keeping guns from rusting in a safe covers the rest.
Silent Dry Hypercube prices in Canada
We stock all three sizes: Small $44.88, Medium $54.88 and Large $64.88, shipped across Canada. Silent Dry lists the specs on its Hypercube page. If you are not sure which size fits, send us the inside measurements of your safe and we will tell you.
Specs from Silent Dry. Prices current as of November 2026.