Shimano CJ-NX40 is a cassette joint compatible with Inter-7 and Inter-4 hubs, designed to facilitate smooth and precise gear shifting on your bicycle. It allows for easy installation of the shifting cable and features a pulley system that ensures efficient power transfer from the shifting lever to the rear derailleur. The cassette joint is specifically designed to work with sprockets ranging from 15T to 23T, making it suitable for various riding styles and terrains.