The First Strike Energy Bar is part of the FSR or First Strike Ration. You will get 4 bars with your purchase. All first strike bars (FSB) are freshest available with manufacture date of 2021/2/3 and a best by date of 2024/5/6! Sterling Foods, LTD. The First Strike Ration, or FSR, is a compact, assault ration designed for use during initial periods of highly intense, highly mobile combat operations. The FSR is substantially reduced in weight and size and enhances soldier consumption, nutritional intake, and mobility.