The present disclosure is directed toward a staple drive assembly for use in a staple cartridge. The staple drive assembly may also be used in a disposable loading unit and/or any other suitable device and can be configured to deploy numerous types of staples and/or fasteners. The staple drive assembly includes an actuation sled and at least one staple driver. The staple cartridge includes a tissue contacting and/or supporting surface having a number of staple cavities wherein each staple cavity is adapted for releasably receiving a staple. The staple cartridge may include a guide channel/knife slot extending from a proximal portion to a distal portion along its longitudinal axis. The tissue contacting portion of the cartridge includes three tissue contacting surfaces which are stepped. The staple drivers may be staggered and may be independent. The height of the staples may vary. The staple drivers may comprise staple retaining features.
