Building or upgrading TT scale model trains? This pack of 40 TT-RP25 wheel sets is exactly what you need! Each set includes a pair of wheels pre-mounted on an axle, ready to drop into your freight or passenger cars. They're one-sided insulated, which is great for digital (DCC) layouts—helps prevent electrical shorts. Made from quality brass by Modelleisenbahnzubehör Müller in Germany, so you know they're precise and durable. Designed for TT scale (1:120) with a 12mm track gauge. They come pre-assembled, so no fiddly tiny parts to put together—just press them into your truck frames. Perfect for replacing old, wobbly wheels, upgrading plastic wheels to metal, or building new rolling stock from scratch. The RP25 profile ensures smooth operation on code 55 or code 80 rails. Suitable for ages 12-16 and up, but really for any serious model railroader. Whether you're a beginner or a seasoned collector, having spare wheels on hand is always smart. These will make your trains run quieter, smoother, and look more realistic. Grab this 40-pack and upgrade your entire fleet!