A mix of 2 - 4 inch anthracite. Probably the best quality available at the price and used mainly for cookers. The ratings below are given to help you decide which is best for you. 3 spots = Excellent, 2 spots = Very Good, 1 spot = Good. Product name Stovesse 3 Heat Output • Burn time • • Ease of lighting • Smokeless Yes Suitable for Cookers