This version of the 550 includes: Powder measure with standard large and small powder bars (small installed), Small bar throws from 2.1 to 15 grains of powder Large bar throws up to 55 to 60 grains of powder. One prime system with large and small priming parts. One large and one small pick up tube Low Primer Alarm  One toolhead One powder die One loaded cartridge catch bin One written instruction manualYou will also need (at a minimum): Die set (dies are not included with the base unit) Powder scale Reloading Handbook Dial caliper Primer flip tray Case lube (for bottleneck cartridges)One set of standard Allen wrenchesI suggest that you also get: Dillon dies, which are designed for high speed use in these machines. Extra primer pick-up tubes, if loading more than 100 – 200 rounds per sitting. If you are loading more than 500 rounds per reloading session, then the RF-100 Electric Primer Filler is an accessory well worth considering. A machine cover to keep the unit dust free.To change calibers, you will need: A Die set for the new caliber. A Caliber Conversion Kit. If you have the optional electric casefeeder you may need a different casefeed plate. Please refer to the caliber conversion chart in the Instruction Manual. If you are using the Mr. Bulletfeeder you made need a caliber conversion.