Product will not be available to ship until end of March. The Blitzkrieg/KynSHOTA(R) PCC Buffer Weight/Spacer 2.5 oz. is inserted into the buffer tube after you insert the buffer and spring, so the weight is in front in the buffer tube. During cycling, the weight is between the bolt and the buffer to prevent tilting of the buffer. Has flats on 3 sides to allow for air flow.&l