This bearing buddy bra is designed to fit the 1.781 or 1.810 bearing buddies. It also happens to fit over top of the 1.980 Accu-Lube / Posi-Lube dust caps very snugly. The cover slips over the end of your bearing buddy to help keep it clean and prevent grease from slinging all over your wheel. This 17B Trailer is also ideal for use on the 1.98 Accu Lube dust caps as it provides an extremely tight moisture barrier to additionally protect your trailer bearings from corrosion. 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!