When your listings have a lot of components, it’s quite handy to have the ability to list multiple items as a kit. Once all your items are part of a kit, you can bind components’ inventories together so there’s no risk of overselling the parent SKU or the child components. With kit assembly, you can transfer the kit component quantity to the parent SKU.
If your kit consists of a smartphone and a case, you must assemble the smartphone kit before shipping it to FBA. The kit assembly feature lets you transfer one unit of each item to the kit parent SKU and ensures that the inventory of each of the components is accurate. This will help you take into account all sales for the components - both individually and as part of a kit.