Rod shaped, stainless steel shot is available in two diameters, 0.3mm and 0.5mm. Both sizes are 5mm long and have blunt ends. This small shot works in magnetic tumblers reaching into and polishing the tiniest small details and settings, without lodging.
How to clean Stainless Steel Shot: Stainless steel shot will not rust but it may turn gray due to accumulated dirt from parts. When this happens the shot will not polish and it often will turn the parts gray too. Stainless steel shot can be cleaned with Coca-Cola® Classic or Trisodium Phosphate (TSP). Empty all water from the tumbler bowl/barrel and fill with Coca-Cola® or Trisodium Phosphate (TSP) to a level about 1/2" over the top of the shot. (If it's a closed barrel, be sure to let the Coca-Cola® sit until it goes flat to eliminate gas.) Turn the tumbler on and let it run for about 15-20 minutes. Then pour off the Coca-Cola®. It will be very discolored. Rinse the shot thoroughly and then you can safely run your parts.
Disclaimer: Gesswein is in no way related to the Coca-Cola® company.