This is untreated Midwest Cotton Duck, which is what has been used to cover canoes of over 100 years. It can be stretched to fit a canoe like a tight glove and is extremely tough and durable. Since it is untreated and of cotton, it is recommended that the canvas is to be treated with a clear wood preservative once on the canoe. The canvas is available in two widths, each of a different weight. The standard for most canoes is 60″ wide and a #10 duck, which weighs approximately 15 ounces per square yard. For square stern canoes and sport boats, we offer a 72′ wide #8 duck which weighs about 18 ounces per yard.