99% clean  Virtually dust-free, won't clog feeders High oil content All natural All black oil sunflowers are not the same. Some mixes contain sticks, cockleburs and other debris. These will clog feeders, and birds will not feed. Some black oils contain up to 20% empty hulls, which are wasted.  Preferred Feeder Type: Tube Feeder (Large Holes), Hopper Feeder, Platform Feeder On the Ground