Posted here is a set of 25 red glass stones from Koplow Games, the NICE DICE(R)Company. These work great for keeping track of character hit points without constantly erasing on your sheet and wearing a hole or leaving behind an ugly smudge mark. These can also be used as replacements or additions for any game that uses glass stones.
Each of these "stones" is made of red glass. Each stone is roughly 15mm in diameter (circular in shape, though not perfect circles) and 8mm tall. The base is flat so that the stones sit nicely and the top is rounded.
These come with a simple 3 inch by 4 inch green velveteen cloth bag for ease of transport.