GSP tops the strength charts among fly-tying threads, and Veevus's slight twist keeps the strand from opening mid-wrap — built for spinning deer hair or any technique that leans on GSP's strength-to-diameter ratio. Specifications Spool Length: 75 meters (60% more than typical spools) Denier: 30, the lightest GSP on the market Construction: Slight twist to prevent the thread from opening; lies completely flat Best for: spinning deer hair and any technique that benefits from GSP's strength-to-diameter ratio. For other GSP-based threads, see Nano Silk Thread 12/0 or Nano Silk Thread 18/0. It lies completely flat, which makes it a smooth surface to spin deer hair against, and at 30 denier it's the lightest GSP currently on the market. A 75-meter spool runs 60% longer than the typical spool from other makers.