The bundling in which shakes and shingles are shipped. In shakes, the most prevalent pack is a 9/9. This describes a bundle packed on an 18" wide frame with nine courses, or layers, at each end. The most common pack for shingles is 20/20. Because of their smoother edges, shingles can be packed tighter than shakes, a bundle of shakes usually contains a net of about 16" of wood across the 18" width of the frame.