After extensive testing and close work with one of the world’s largest thread manufactures, Fuji and Anglers Resource have developed a unique wrapping thread made of specialized polyester that accepts finish beautifully and resists UV, aging and abrasion better than Nylon. Polyester is the number one thread choice for any outdoor application and in particular the marine industry for its ability withstand harsh environments including saltwater and scorching UV rays. ULTRA Poly is a pleasure to use and brings a bright, colorfast finish to any rod building project. And, thanks to the high-tech facility manufacturing ULTRA Poly, you can count on consistent colors and exact performance from spool to spool. Model: UPA00, Size A, Length: 100m, Made in Japan After extensive testing and close work with one of the world’s largest thread manufactures, Fuji and Anglers Resource have developed a unique wrapping thread made of specialized polyester that accepts finish beautifully and resists UV, aging and abrasion better than Nylon. Polyester is the number one thread choice for any outdoor application and in particular the marine industry for its ability withstand harsh environments including saltwater and scorching UV rays. ULTRA Poly is a pleasure to use and brings a bright, colorfast finish to any rod building project. And, thanks to the high-tech facility manufacturing ULTRA Poly, you can count on consistent colors and exact performance from spool to spool.