GIVI T507 Waterproof Inner Bag for Trekker Outback 48 Side Case Waterproof liner/exterior bag 45 liters Size 17.7" L x 11" W x 13" H Roll down closure system to ensure fully waterproof functionality Fits Givi Trekker Outback 48 Liter OBK48A OBK48B Saddlebag It can also be used on the lid of the topcase or saddle bag, fixing it with the included elastic straps