Ultra light main gear shaft of ABU 1500C, 2500C made of extra strong duralumin (ESD), to remove 8g weight from the part. Fits to all ABU 1500C, 2500C, 3500C reels with IAR, instant-anti-reverse. Not fit to 1600C or 2600C thumb bar clutch models. 3.2g. Genuine brass shaft 10.2g. Clutch return posts are increased from 2 to 4, and you may return clutch faster.