GREASE KEEPER snug fitting steel dust cap has grease zirk and pressure relief valve built in. Protects and extends bearing life. Zirk permits frequent greasing and relief valve allows escape of excess pressure. Zinc finish. Includes two caps and two vinyl covers. Fits in same applications as DL 6502, 6503 and 6507 trailer wheel bearing sets, for spindles of 1" and 1-1/16".