Shimano #BNT2949 Roller Clutch Bearing, 10 X 16 X 8 mm. This bearing is used in several of the Shimano level wind reels that have “instant anti-reverse.”  Please check the schematics for your reel for the correct part number.  If you need schematics, here is a link, www.reelschematics.com.  If you have questions or need more assistance, please send us an email and we will get right back to you.  

A good aftermarket substitution is #S-EWC1008.  This stainless-steel version can be used in a number of reels that use a 10 X 16 X 8mm clutch bearing.