Helfpul: Even a drop of moisture can fog up a headlight lens when mixed with heat. By adding some silica packs in the underbelly of your headlight housings though, you can help prevent that mess before it happens. These 10 gram packets can absorb any ambient water vapor within 2 hours, and will stay dry even at maximum saturation. Recommended: Sold in pairs, we recommend one pair per headlight for the best results. One near the housing caps, one on the bottom of the headlight.