All Poly-planar speakers are designed to withstand the harsh marine environment. Corrosion proof grills and hardware. Polypropylene cones, mylar tweeters, and plastic frames. 5-1/4" two way speakers can be conveniently used as a freestanding enclosed speaker or the back cover may be removed and the speaker mounted as a flush model. Low magnetic field. 140W per pair. Sold in pairs.