If you're maintaining trailers or doing wheel bearing work, this Fulton grease cap is exactly what you need! The 3.125-inch size is a standard dimension that fits many trailer wheel hubs perfectly. This simple but crucial component protects your wheel bearings from dirt, moisture, and contaminants that can cause premature wear and failure. Installation is straightforward - just press it onto your wheel hub after packing your bearings with grease. The quality is typical Fulton - reliable, well-made, and built to withstand the rigors of trailer use. Whether you're replacing a damaged or lost cap during maintenance, or building a trailer from scratch, having the proper grease caps is essential for protecting your wheel bearings and ensuring smooth, safe towing. The part number 001609 makes it easy to reorder or verify compatibility. Such a small, inexpensive part that plays a big role in maintaining your trailer's reliability and safety on the road. Always good to keep a couple spares in your toolbox for when you need them during trailer maintenance or repairs. Fulton has been making quality trailer components for years, so you can trust this grease cap to do its job properly and last through many miles of towing adventures.