The Dillon RL 550B Case Feeder .38 / .357 Caliber Conversion is a kit of the calibre-specific parts required to feed and insert the cartridge cases into the shell plate of the Dillon RL 550B progressive reloading machine. These parts complement the RL 550B Case Feeder, and are required for each different handgun caliber loaded on the RL 550B (when using the electric case feeder).