Slick Rock Concrete KRL22SEING-COALGRAY 22" x 10" Square Coal Gray NG IID RidgeLine Fire Bowl, Electric Ignition Burner. Our RidgeLine Fire Bowls are a gorgeous addition to anyone seeking to enhance the appearance and character of their outdoor area. Running on propane or natural gas, Slick Rock’s fire bowls are safe and simple to operate. Each RidgeLine Fire Bowl is crafted with top-quality cast concrete. The passion that we have for our concrete products shines through the excellent quality of our fire bowls. We manufacture our fire bowls locally, using the finest materials and the best quality workmanship you can find in the industry.