Bearing Buddy premium quality stainless steel protectors are real easy to install and give perfect grip and cover with continuous enhanced lubrication to save you a peace of mind while on road or in water. Bearing Buddies for Boat Trailers Trailering, even a short distance, heats the hubs. When the wheels are submerged during launching, the hubs suddenly cool and the air inside the unprotected hubs contracts, forming a vacuum which draws in water through the rear seals. There is no such thing as a rotating seal that stays perfect. Water and grit thus drawn into the hubs relentlessly destroy bearings. When properly installed and maintained, these little marine Bearing Buddy guard wheel bearing system from failure and eliminates bearing repacking. Boat trailer wheels can be completely submerged. Utility Equipment, ATV, Horse, Camping, Snowmobile and other occasional used trailers These tow trailers, because they are not used regularly, are also subject to bearing corrosion and failure from condensation moisture from air sucked into hot hubs as they cool. Moisture stays in the hubs causing rust and pitting until they are reheated when the trailer is used again. On any vehicle, protecting your wheel bearings from dirt, dust, water, salt, sand and other contaminants is critical, so when it comes to using grease caps, you don't have much of a choice. That's their job. You either use them and your wheel bearings will remain useful, or you don't, and your wheel bearings wear out in a hurry.