The topeak mtx trunk bag dxp is ideal for light mountain touring road touring commuting and errands with a capacity of 226 litres the mtx dxp bag is the biggest of the topeak trunk bags plus it is weather resistant so you know that everything you put it there will be kept safe and dry it features elastic top bungees for storing your cycling jacket plus a detachable shoulder strap so you can take the pannier bag off the rack and carry it with you all of the topeak bags and racks use a q