Upgrading your mountain bike's brakes? This is the serious stuff – a Shimano XTR RT-MT905 Ice Technologies Freeza disc brake rotor. It's brand new in the box, never used. The Freeza technology is awesome – it helps keep the rotor cooler during heavy braking, which means more consistent power and less fade on long descents. It's a 6-bolt mounting type, so make sure it fits your hubs. You can choose between 180mm and 203mm sizes (check the listing for which one this is). Designed for mountain bikes and downhill bikes where braking performance is critical. Part of the top-tier XTR series from Shimano. If you're building a high-end bike or just want the best heat management for your brakes, this rotor is a fantastic choice. Lighter, cooler, and more powerful braking for those gnarly trails. Get ready to stop on a dime!