This is a pack of 10 brand new 6003-2RS ball bearings. The dimensions are standard: 17mm inner diameter, 35mm outer diameter, and 10mm width. The \2RS\ means it has two rubber seals (one on each side) to keep grease in and dirt/moisture out. These are super common bearings used in all sorts of stuff - skateboards, electric motors, pulleys, conveyor rollers, you name it. Brand is NY-Supplies. Having a 10-pack is brilliant because you can use a couple for your project and have spares for next time, or replace several at once in a piece of equipment. They're premium sealed, so they're ready for tough conditions. Just press them into place. A super useful and versatile hardware item for any DIYer, mechanic, or maker's workshop.