Castelli Pro Seamless Arm WarmerCastelli worked with pro cycling team, The INEOS Grenadiers, to develop lightweight warmers that provide warmth and moisture-wicking properties while remaining lightweight and flexible. The Castelli Pro Seamless Arm Warmer is constructed using a unique blend of polyester, nylon and lycra for an optimal combination of stretch, warmth and moisture management. These leg armers are the ideal choice for early morning rides in cool weather and are packable so you can take them off and stash them in your rear jersey pocket when they are not needed. FeaturesTemp10deg-20 degC / 50deg-98degFMid-weight fabric for comfortMaterialsUnique polyester/nylon/Lycra(R) 78%/15%7% blendPackableFolds up extra smallSizingSizeSmall /MediumLarge/ Extra LargeChest100-155 lbs155-175+lbs | Castelli | Pro Seamless 2 Arm Warmer Men's | Size Small/Medium in Black