If you are looking at bushings, you probably don't need an explanation of what they do. Or maybe you do, either way, we are not going to judge you. The bottom bushing for most skateboard trucks is typically a cylinder shape while the top is a conical shape. This helps keep your board riding smooth. Softer bushings (88A-94A) are used for lighter riders or riders who like loose trucks. Harder bushings (95A-99A) are for riders who want really stiff trucks for a stable ride. This listing includes 20 Medium 96A bushings, enough for 10 trucks.