Hey it's an O-ring, not much to say about that but they fit well and keep the gear oil in the axle and not on the wheel and/or driveway. It's a good idea to have them on hand if you need to pull the waves for any reason. They only break if there is no replacement available.
π§ Enhance Performance and Style with Yukon Gear & Axle (YP C1-GM8.5-R) Chrome Cover for GM 8.2/8.5/8.6 Rear Differential
8 Review
CDHPOWER Black Aluminum Mag Wheels - 66Cc/80CC Gas Motorized Bicycle: Enhance Your Ride!
13 Review
π B&M 80775 Unimatic Automatic Shifter: Sleek Black Design for Effortless Gear Changes
9 Review
π§ High-Quality Moroso Gasket for E40D/4R100-Ford Transmissions (93105)
9 Review