There are many types of seals. Enduro’s seals are usually either LLU (usually the MAX type bearings) or LLB (better for hubs). The outer sealing lip repels dirt and water while the inner sealing lip retains the grease.
6903 LLU MAX | 17 x 30 x 7mm | Blueseal Bike Bearings
6903 LLU MAX | Frame Pivot Bearing | by Enduro
PAIR OF DUNLOP 61903-2RS (6903-2RS) THIN SECTION HIGH QUALITY BEARINGS 17X30X7MM
Bike Bearings 18307 6903-2 / 18mm X 30mm X 7mm Rubber Sealed MR18307
6903 2RS or LBLU | Wheel Bearing
