Alpinestars Purpose Mid Layer Jacket The Alpinestars Purpose Mid Layer Jacket is constructed from a 250gsm polyester spandex blend to help retain body heat. The mid layer can be worn alone as a casual jacket or under your motorcycle jacket for extra warmth. Features: 250gsm 95 ployester, 5 spandex 2-way main zipper Hand warmer pockets Seamless Lycra cuff with thumb loop