Providence made my search for hardened feet for my shopmade measuring tools real easy - as my Uni had a complete overhaul of its big A/C pump and fan assemblies. 20 kg of different ball bearings in the metals recycling dumpster will provide all the balls I might need, as well as the inner and outer races will come in handy as precision ground spacers/ parallells/ "poor man's gauge blocks" in the shop. Material: SAE 52100 Chrome steel, through-hardened to about HRC 60-64. How-to: 1) Pry away the metal shield or plastic seal on the side. 2) Drill/ grind away the ball cage's rivets and tear cage out. 3) Move the balls together, press inner race from the balls, towards the outer race's void, thus releasing the balls. 5) Rinse, repeat and repurpose.