A fastener cartridge assembly. The fastener cartridge assembly can comprise a fastener, a cartridge body, and a tissue thickness compensator. The fastener can comprise a base, a first leg extending from the base, and a second leg extending from the base. The cartridge body can comprise a fastener cavity for receiving the fastener and a trajectory control for controlling the trajectory of the first and second legs of the fastener. The fastener can be removable from the fastener cavity along a fastener axis. The trajectory control can extend inwardly toward the fastener axis and can bias the first leg and the second leg toward alignment with the fastener axis when the fastener is positioned in the fastener cavity.