These are simply abbreviations for your van's dimensions. L refers to your van's length or wheelbase. H refers to your van's roof height. As a general rule the smaller the number the smaller the size. L1 = Short Wheelbase (SWB) L2 = Medium Wheelbase (MWB) L3 = Long Wheelbase (LWB) H1 = Low Roof H2 = Medium Roof H3 = High Roof If you are not sure what your van's wheelbase or roof height is, please contact our customer team who will be happy to assist. Products without an L or H value assigned are universal fitting and should fit most vans.