100% Cotton String - 3000 yards/spool approx. This is the same untreated, non-mercerized 100% cotton string used by the major safety fuse manufacturers such as International, Longhorn, Meremac, American Visco, etc.. It comes on 7 oz spool bobbins spinning weights, 16-2. With a tensile strength of approx 2-3 lbs. For comparison, note the final counter-wrap on visco safety fuse which is generally the 16-2 weight. Clean burning, leaving no ash - 100% cotton. Use it for all your ignition requirements; spinning safety fuse, blackmatch, piped match (quick match), Thermalite, Flying Fish fuse and other special effects fuse, etc.. Firefox will be offering professional fuse spinning machinery in the Fall of 2010 Ask us!