Electrical service in China is 50Hz, 240V as compared to 60Hz, 110V in the U.S.
Nevertheless, if you are traveling to China, you may not need any adapters. Check the devices that you want to plug in. If they say 50-60Hz, 110-240V then you are all set. You don't need anything else. Furthermore, our plugs will fit into their outlets. It doesn't look like it, but they do. (At least our 2-prong plugs fit. I don't know about 3-prong plugs.) I had four electrical devices with me: laptop computer, Blackberry, AA battery charger, and an electric razor. They all worked just fine without any adapter.
(Thanks, Susan, for giving me this tip before I went.)
