Bearing is packed with heavy duty premium marine grease and with the addition of special complex thickeners which allows it to be virtually waterproof, Nitrile butadiene rubber double-lip oil seals help prevent abrasives, corrosive moisture and other harmful contaminants from entering bearings, To further help keep any moisture out, we have gone from 30% grease filling to a 60% for harsh conditions, The special v-groove on the inner race is better for resistance to water intrusion, Provides unsurpassed rust and corrosion protection, Factory-Links ball bearings are specially designed for Off-Road use.