A fastener cartridge assembly (20200; 20600), comprising: a cartridge body (20210; 20610) comprising a plurality of fastener cavities (20212; 20612); a plurality of fasteners (20230; 20630), each fastener (20230; 20630) comprising a first leg (20232; 20632) and a second leg (20232; 20632), wherein each fastener (20230; 20630) is moveable from an unfired configuration to a fired configuration; a tissue thickness compensator (20220; 20620) releasably secured relative to the cartridge body (20210; 20610), wherein the tissue thickness compensator (20220; 20620) comprises: a plurality of first clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620); and a plurality of second clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620), wherein each first leg (20232; 20632) is configured to move along a respective first clearance aperture (20224; 20624) and each second leg (20232; 20632) is configured to move along a respective second clearance aperture (20224; 20624) when each fastener (20230; 20630) moves from the unfired configuration to the fired configuration; and wherein each of the first leg (20232; 20632) and the second leg (20232; 20632) of each fastener (20230; 20630) is at least partially embedded into its respective clearance aperture (20224; 20624) in the tissue thickness compensator (20220; 20620) when each fastener (20230; 20630) is in the unfired configuration. a cartridge body (20210; 20610) comprising a plurality of fastener cavities (20212; 20612); a plurality of fasteners (20230; 20630), each fastener (20230; 20630) comprising a first leg (20232; 20632) and a second leg (20232; 20632), wherein each fastener (20230; 20630) is moveable from an unfired configuration to a fired configuration; a tissue thickness compensator (20220; 20620) releasably secured relative to the cartridge body (20210; 20610), wherein the tissue thickness compensator (20220; 20620) comprises: a plurality of first clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620); and a plurality of second clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620), wherein each first leg (20232; 20632) is configured to move along a respective first clearance aperture (20224; 20624) and each second leg (20232; 20632) is configured to move along a respective second clearance aperture (20224; 20624) when each fastener (20230; 20630) moves from the unfired configuration to the fired configuration; a plurality of first clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620); and a plurality of second clearance apertures (20224; 20624) defined within the tissue thickness compensator (20220; 20620), wherein each first leg (20232; 20632) is configured to move along a respective first clearance aperture (20224; 20624) and each second leg (20232; 20632) is configured to move along a respective second clearance aperture (20224; 20624) when each fastener (20230; 20630) moves from the unfired configuration to the fired configuration; and wherein each of the first leg (20232; 20632) and the second leg (20232; 20632) of each fastener (20230; 20630) is at least partially embedded into its respective clearance aperture (20224; 20624) in the tissue thickness compensator (20220; 20620) when each fastener (20230; 20630) is in the unfired configuration.