An end effector comprising an anvil, a staple cartridge jaw, and a firing member is disclosed. The an anvil comprises staple forming pockets. Each staple forming pocket comprises a pocket base. The staple cartridge jaw comprises a staple cartridge comprising a longitudinal slot, a first longitudinal row of staple cavities, a first staple, a first staple driver, a second longitudinal row of staple cavities, a second staple, and a second staple driver. The first staple comprises a first unformed height and the second staple comprises a second unformed height that is the same as the second unformed height. The firing member is configured to lift the first staple driver and the second staple driver toward the anvil during a staple firing stroke. The first staple is deformed to a first formed height. The second staple is deformed to a second formed height that is different than the first formed height.