WEATHERSHIELD CHIMNEY CAP MODEL WSA is a great cap to use when replacing a chimney cap for a solid pac Class A chimney. Its 304 stainless steel construction assures superior corrosion resistance to weather and the hostile flue gas environment. Despite adverse weather, the WeatherShield will not rust. For use with solid pack Class A, masonry and single wall chimneys to keep the rain, snow, leaves and animals out, but keeps sparks in.