The aluminum kits you buy online are all-inclusive. What this means for you is that they are ready right out of the box. You do not have to purchase any more parts to build the greenhouse, The box includes everything minus the base of the greenhouse. Extra hardware is included in the kit. This means that if you ever want to add on to the greenhouse, the adapters and connectors are already in the box. This takes the guess work out of what to buy to put on additions.