This trolley holds following combinations of products: Three pcs of 4 tier straight seated risers, Or two pcs 4 tier wedged seated risers and one straight tier riser or two straight 4 tier and 1 wedged 4 tier. There is also an optional ISSTRAP (Strap with Ratchets) that can be added to tie down the risers to your trolley. The strap is 5.2m long and 2mm thick and make from high strength polypropylene filament yarn