Releasable tissue thickness compensator and fastener cartridge having the same

The invention provides a releasable tissue thickness compensator and a fastener cartridge having the same. The fastener cartridge assembly is for use with a surgical end effector. The fastener cartridge assembly can comprise a cartridge body (5650), fasteners, and a layer of material releasably secured to the cartridge body. The layer of material can be a tissue thickness compensator (5658). The cartridge body, the fasteners, the tissue thickness compensator and/or the end effector can comprise various features to releasably secure the tissue thickness compensator relative to the cartridge body. For example, the cartridge body can comprise slots (5656), projections (6048), cavities (5948), drivers (5920), locks (6320), and/or keys (6353), the fasteners can comprise barbs (6296), and/or the tissue thickness compensator can comprise mounts ((5660), (5760), (5860), (5960)) and/or connectors (6480).