Important note: you only get one mug! If you want to have two and fit them together, you'll have to order two, probably in different colours.
A coffee mug shaped like half of the symbol for yin-yang. Bring some balance to your hot drinks. This should comfortably hold about 250mL (8½ fl. oz.), but that might vary depending on the glaze thickness. There's also a "clockwise" variant, which may be more comfortable depending on which hand you hold cups in: http://shpws.me/paUU And if you prefer something smaller, there's an espresso-cup version too: http://shpws.me/pZWx