Product Description For the really tough guys: the 1/8" Track Cog by Surly The Track Cog is only made for really tough guys, who love the feeling of riding in pre-freehub times. It truly requires a lot of practice and some hardened leg muscles - but when you've got it down, you'll have a lot of fun. Technical Information: Material: steel (SCM415 CroMoly) Compatibility: 1.375" x 24 tpi ISO hubs Tooth Count: 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 Tooth Thickness: 1/8" Thread Width: 7.4 mm Features: Fixed Gear (without freehub) for Surly hubs use only with lockring for singlespeed chains Manufacturer Numbers: 13 tooth: FW2061 14 tooth: FW2062 15 tooth: FW2063 16 tooth: FW2064 17 tooth: FW2065 18 tooth: FW2066 19 tooth: FW2067 20 tooth: FW2068 21 tooth: FW2069 22 tooth: FW2070 sold-out Contents: 1 x Surly Singlespeed Track Cog, 1/8" not incl. lockring Manufacturer: Surly 6400 W 105th St Bloomington MN 55438 USA derby@surlybikes.com Distributor: Cosmic Sports GmbH Leyher Straße 47 90763 Fürth Germany info@cosmicsports.de