Grantwood Technology TuneBand for iPod Nano 1st/2nd Generation, Premium Armband Compatible with Nike Plus iPod (Models A1137 and A1199), Black COMPATIBILITY: Fits a bare iPod Nano 1st and 2nd Generation *only*. It has the following model number on the back: A1137 or A1199 ACCESSIBILITY: Durable silicone skin allows access to all ports and buttons. Enjoy unobstructed access to your music! COMFORT: One (1) soft, elastic Velcro strap accommodates arm circumferences between 11" - 14" (about 28cm to 35cm). See product description regarding longer and shorter straps. CONVENIENCE: Two-piece design means you can use the silicone skin as an everyday case, and then attach the elastic strap when exercising. NIKE+IPOD: Many customers use the Tune Band with the sensor from the Nike iPod system (sold separately on Amazon). Also search Amazon for "Shoe Pouch for Nike iPod".