This bearing buddy bra is designed to fit the 1.781 or 1.810 bearing buddies. This cover slips over the end of your bearing buddy to help keep it clean and prevent grease from slinging all over your wheel. It also happens to fit over top of the 1.980 Accu-Lube / Posi-Lube dust caps. When used with a 1.98 Dust Cap Accu-lube Fits Most 4 Lug and 5 Lug Trailer Hubs it gives you that added protection from the Water and Sun to ensure a longer life of your Dust Cap. This is actually the main purpose for us selling it, because it makes a significant difference when using the accu-lube caps. While the center caps themselves are not very expensive either, when they fail, water is allowed to enter your Bearing Chamber. When using this 17B Bearing Protector Cover, the center plug is not likely to fail, meaning longer bearing life, and a more confident trailer owner!