Slick Rock Concrete KRL29SMNG-GRAY 29" x 13" Square Gray NG RidgeLine Fire Bowl, Match Lit. 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.