While the 18M offers a level of water resistance, it is recommended you protect your unit from both weather elements and the general elements of the show. If you are expecting rain, it is strongly recommended you cover your units as water will damage your system.
To assist in protecting your modules, COBRA does offer two protection options, including the protective silicone boot, and armored case. For a cost-effective protection option, you can use a 5-gallon bucket placed upside down over your module.