If you're into bike maintenance or repair, these steel bearing balls are one of those basic supplies that's good to have on hand. Each ball measures 5.5mm in diameter (about 0.22 inches) with a silver tone finish and hardness level of 61-66, which is standard for bicycle applications. You get 270 pieces in the package (±2% variance), which should be plenty for multiple repair jobs or to share with fellow biking enthusiasts. They're made from quality steel material that can handle the stress and rotation of bike wheel bearings without deforming or wearing down quickly. Perfect for replacing lost or damaged balls in your existing bearings, or for DIY projects where you need small, uniform steel balls. When your bike starts making weird grinding noises or doesn't roll as smoothly as it should, often it's the bearing balls that need replacing. Having these on hand means you can fix the issue quickly without waiting for parts to arrive. They're also useful for other mechanical projects beyond bikes - anywhere you need small, precision steel balls for bearings or mechanisms. The package comes with just the balls themselves, so you'll need the proper tools and knowledge to install them in your bike's bearing assemblies. For the price, having a supply of these handy can save you multiple trips to the bike shop for simple bearing maintenance.