These are 100% premium grade oak hard wood pellets. Used for fuel pellet stoves, these are a great source of clean, medium grade oak sawdust for all wood loving mushrooms. Simply soak in hot water and they "fall apart" into a very manageable sawdust substrate. Great for making sawdust spawn blocks, or as a supplement to other substrates for wood loving mushrooms. Approximate dry weight is 2.5 pounds per bag.