A cartridge assembly (104; 204) comprising: a cartridge channel (112; 212) including a bottom wall (144:244) and side walls (132: 146:252) defining a recess, each of the side walls having a first end secured to the bottom wall and a second end spaced from the bottom wall, the second end of each of the side walls defining a support surface; a staple cartridge (106;206) defining a longitudinal axis and including an upper wall defining a tissue contact surface and side walls, the upper wall extending radially outward of the side walls of the staple cartridge to define a longitudinally extending shoulder, the cartridge assembly further including a support plate secured to the staple cartridge wherein the support plate includes a bottom wall, and first and second side walls that define a U-shaped channel dimensioned to receive the staple cartridge, each of the first and the second side walls of the support plate having a first end connected to the bottom wall of the support plate and a second end having a support flange wherein the support flanges are supported on the support surface of the cartridge channel ; and a compression member (116; 216) supported on each of the support flanges of the support plate each of the compression members being positioned between one of the shoulders of the staple cartridge and one of the support flange of the support plate, each of the compression members including a body having an elongated upper portion positioned to engage the shoulders of the staple cartridge and a lower portion defined by a plurality of spaced fingers and grooves, the staple cartridge being dimensioned to be received within the recess of the cartridge channel such that the shoulders of the cartridge rest atop the elongated upper portion of each of the compression members (116; 216). a cartridge channel (112; 212) including a bottom wall (144:244) and side walls (132: 146:252) defining a recess, each of the side walls having a first end secured to the bottom wall and a second end spaced from the bottom wall, the second end of each of the side walls defining a support surface; a staple cartridge (106;206) defining a longitudinal axis and including an upper wall defining a tissue contact surface and side walls, the upper wall extending radially outward of the side walls of the staple cartridge to define a longitudinally extending shoulder, the cartridge assembly further including a support plate secured to the staple cartridge wherein the support plate includes a bottom wall, and first and second side walls that define a U-shaped channel dimensioned to receive the staple cartridge, each of the first and the second side walls of the support plate having a first end connected to the bottom wall of the support plate and a second end having a support flange wherein the support flanges are supported on the support surface of the cartridge channel ; and a compression member (116; 216) supported on each of the support flanges of the support plate each of the compression members being positioned between one of the shoulders of the staple cartridge and one of the support flange of the support plate, each of the compression members including a body having an elongated upper portion positioned to engage the shoulders of the staple cartridge and a lower portion defined by a plurality of spaced fingers and grooves, the staple cartridge being dimensioned to be received within the recess of the cartridge channel such that the shoulders of the cartridge rest atop the elongated upper portion of each of the compression members (116; 216). <EOS>