Samix TRX-4 Aluminum Hex Adapters add 8mm of length to your track width, and add minimal weight. The hubs weigh 9 grams total, so they add minimal rotating weight to the drivetrain. They are easy to install using the stock hardware and will help to increase the overall stability of the model. Features: 8mm thickness Made of high quality CNC machined aluminum Direct fit standard TRX-4 Available in black, grey or silver anodized colors, with silver chamfered edge Width marked on the side for easy identification