This  is a great item! Get your old bike riding like new again. This is a new in the package 7pc Clutch Friction Disc Set for the 1975 DT400( DT400B) and 1976 DT400 (DT400C). Please note these will not fit the later 1977 1978 DT400 as the used a different clutch friction disc.   Start enjoying your bike...get the back tire spinning..not your clutch! If your clutch feels jerky or slipping this is the fix. This is an easy swap for the home mechanic to do..or get your local shop to help you.  If you are riding, restoring or racing you and your bike will be happy with a new clutch! Your bike probably still has the old original clutch plates in it! The top-quality new clutch friction discs set is an important part of getting your engine power to your back wheel smoothly..and allow you to enjoy the trails, woods or track. Your clutch disc set will be mailed to you new in the package. Top quality aftermarket item.  Correct replacement for Yamaha part # 163-16321-10-00,  163-16321-10 which was superseded by # 5Y1-16331-01 That's is it! We only sell the best. Thank you, and we look forward to doing business with you!