This is a clean cast iron rear rim or snowflake rim as I call it. Will fit all twins 1970- 1984 . The snowflake design wheel came out in 1978 and will fit the years years mentioned earlier. Rim size is 2.5 x 18 . The rim is a drum brake rear rim. This rim is in straight condition. I consider this rim to be 90- 95% straight as only new wheel is 100% straight. I warranty this wheel to not cause any handling issues. It will need to be mounted on the bike and ridden for warranty purposes. This is a silver wheel. Their were gold ones as well. Rim edge very minor blems from age and use. The drive spline is in good condition. BMW gets nearly $ 800. for this rim now. I have a front snowflake wheel as well. Contact me with any questions you may have.