T506 Waterproof Inner Bag 35 Litres for Trekker Outback 37 Bag with rectangular base 35 ltr for Trekker Outback 37 ltr. It can be used on the lid of the top-case or as a saddle bag, fixing it with standard elastic straps. As standard: - Roll down closure system to ensure fully waterproof functionality • Air vent • Shoulder strap • Two tubular fluorescent yellow elastic straps, with hooks.