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
ENDURO Bearing 6903 LLU MAX BO ABEC3
Mavic Hub Bearings 6903 Hub Bearings 17x30x7 6903 X 2
NTN BEARINGS FOR BICYCLES LLB & LLU WHEELS, HUBS, FREEHUBS, BOTTOM BRACKETS BB30
6901 LLU MAX | Frame Pivot Bearing | Enduro
