LT-S300 Rimmed Sleeve for the Rifle Trainer Cartridge LT-223. The LaserLyte LT-223 is the foundation training cartridge for an array of new Training Cartridge Sleeves for many popular hunting calibers. The LaserLyte Training Cartridges in the new rifle calibers give young and first-time shooters the opportunity to practice the fundamentals, as well as, refine trigger control skills for shooters of all levels. The rimmed sleeves are made of solid brass and work perfectly in all bolt-action rifles. The LT-223, in combination with any of the new Training Cartridge Sleeves and the LaserLyte Trainer Target, can improve the success of any hunt or target shoot with realistic, anytime-anyplace, affordable training.