Want a perfectly flat base for your miniatures? Look no further than Renedra. They are the standard for historical miniatures, available in a variety of sizes they are 1.5mm thick and made from the same hard plastic as most 28mm wargaming miniatures.
This is one packet of 40 x 20mm bases 20 bases in total. They may be off the sprue/loose depending on availability. We use these for Warmaster.