We recommend 1 cartridge for every 12? interval for curved application; 9? interval for straight run. Be sure to include 1 additional cartridge to your total count. If your wall is sharply curved, add additional mounting hardware at every turning point or at point of track connections. This bracket needs to work in conjunction with ceiling mount cartridge CC3,CC2, CC1 or double track cartridge DC3,DC2, DC1. To order other optional items, shop under “Optional Accessories” before checking out.