ADIDAS by STELLA McCARTNEY Handbags. The adidas by Stella McCartney Gym Bag comes in a medium size and features a spacious main compartment with extra wide opening. Designed for To & From Smart Separation Detachable bag in main compartment can be used for shoe storage and to separate fresh and used gear, media zip-pocket for quick access to your phone and keys Exterior side pocket for various storage. 100% Polyester