The expandable top box. The brand new design allows you to effortlessly collapse and expand the rigid top box according to the amount of luggage you want to carry. 3 Sizes in one top box. Size L: At it's most streamlined height, this box offers a volume of 46l. A practical size that allows you to carry all the things you need daily. Size XL: At it's middle setting the box expands to 52L. This comfortably allows you to store up to 2 XXL helmets. Size XXL: At it's maximum capacity the 58l top box, truly shows its versatility.