The rigging foam is durable, sturdy and reusable. Includes four (4) each of multiple colors. The small size is mostly to store rigs of multiple nymphs, and tandem rigs for small flies like midges. The rigging foam allows you to pre-rig flies and quickly change them on the water. The foam spools are 1 3/4 inches in diameter, 3/8 inch thick with a 5/8 inch diameter hole for placing them on a tippet type holder.