A surgical stapling unit (100) that includes a first jaw (102) and a second jaw (104) movable to each other to perform a surgical stapling operation whereby staples are fired into the tissue, where the unit of load comprises: a cartridge assembly (200) bearable in the first jaw and the second jaw, in which the cartridge assembly has a contact surface with tissue defining an elongate groove (234) extending longitudinally and a plurality of retention slots (222) of staples formed therein, wherein the cartridge assembly includes a surgical staple (223) loaded in each staple retention slot； an anvil assembly (300) bearable in another jaw, the first jaw and the second jaw, wherein the anvil assembly includes an anvil plate having a contact surface with tissue defining an elongated groove that extends longitudinally and a plurality of stapling cavities； a surgical reinforcement (500) removably disposed against at least one of the tissue contact surfaces of the cartridge assembly and the tissue contact surface of the anvil assembly, wherein the or each surgical reinforcement includes a configured body part and sized to cover the plurality of staple retention grooves or the plurality of staple-forming cavities of the respective cartridge assembly and anvil assembly, wherein the body part defines a distal edge and a proximal edge； a respective length of suture thread ("S2") which ensures a respective surgical reinforcement against at least one of the tissue contact surfaces of the cartridge assembly and the tissue contact surface of the anvil assembly, where the suture is extends transversely through the respective surgical reinforcement； and a retention feature (114) that ensures the length of suture thread to the respective cartridge assembly and anvil assembly in which the retention feature comprises a plurality of grooves formed on a side surface of the respective cartridge assembly and assembly of anvil, where the grooves are formed near opposite distal lateral edges an
