Is the radio system waterproof?

The receiver itself is not waterproof, but it can still be used in wet conditions as long as it is inside the sealed receiver box that is standard equipment in all Traxxas waterproof models. This is true for all Traxxas receivers; it's the waterproof box that encloses the receiver that allows it to be used in water, mud and snow. The transmitter is not waterproof, so use caution when operating your model in wet conditions, and do not operate your model in the rain.