Hello Claire, great question. If you have the older Filtex metal door faceplates on your wall you need a large 'tapered cuff' hose end. Go here https://builtinvacuum.com/help/filtex.html#hoses
and look down a bit to basic hoses. If you have the metal inlets then load that hose into your cart and then built the entire kit a-la-cart using the accessories link on the left side navigation. The link in the answer also informs how to upgrade the older inlets for those who need to vacuum carpet.