Hapstone Linear Ball Bearing Pivot Unit For Sharpening SystemsUpgrade your Hapstone M2 sharpening system with the Hapstone Linear Ball Bearing Pivot Unit. This optional upgrade is designed for the first version of the Hapstone M2 that used a PTFE lining. The Linear Ball Bearing provides a smooth shaft movement and is maintenance free, eliminating the need for lubrication. This pivot unit is now a standard feature in all new Hapstone systems, ensuring a high quality sharpening experience every time. Upgrade your