It says:
This converter and adapter plug set should only be used with class II electronics up to 0.4A (110V-MAX. 50W). common class II electronic devices include but are not limited to: travel irons, hair dryers, electric razors and similar devices with 2-pronged plugs not relying on connection to the grounding terminal of the AC main power system for operator safety.
AND
This converter and adapter plug set cannot be used with class I electronics and appliances. Common class I electronic devices include but are not limited to: personal computers, dvd players, mp3 players, household appliances, appliances with 3 pronged plugs and similar devices.

It sounds like you can use it for a hair dryer, which I'm not bringing but not for an ipod or cell phone (which I am)

Can you tell me what this warning means? I bought the voltage converter and adapter set at Target. It has 4 different plugs and a dual wattage converter.

I believe the answer is that your cell phone and iPod already include a transformer for charging that alters the incoming voltage. Look on the charging units that came with your phone and ipod and you'll see that they specify voltage between 100 and 240 (approx). All that you really need is an adapter plug that will let you plug the equipment in.
Your last sentence should read: " It has 4 different plugs and a dual VOLTAGE converter."

The converter says

DUAL WATTAGE CONVERTER

?

Maybe I (as a politician would say) "misspoke." I see there's a product advertised as follows: "Dual Watt Converter changes 220v foreign electricity into 110v for most appliances made in the USA rated 0-2,000 watts."
But the formula is Watts = Volts x Amps
When you convert the voltage from 110 to 220 you change the wattage too, though that's not what you'd be aiming at. Here I reach the limit of my understanding, and we need help from someone more informed than me.
Anyway, I am fairly sure of my main point: You don't need to convert the voltage on electronic items like cell phones, camera chargers, ipod adapters, etc. They are built for dual voltage, and all you need is an adapter to plug the thing into a wall outlet.

Return the converter - you don't need it. As Will says, the items you are taking already have a converter as a part of the charger.

you don't need it....read your insturction books for phone, etc....you will see that you can just plug them in and they will charge....what you may or may not need, depending on the hotel outlets, is a plug adapter...this converts your two prong regtangular plug into a thai plug that is two round plugs....many hotels have the usual american style recepticals so nothing is needed....marriott is one of those...often the hotel will loan them too....most hardware stores carry these apdapters...they are cheap....there is a "universal" one that is available for about $50, but i find it to be a pain...

OK! got it.
leave the converter at home and take the adapter that has the round prongs and is marked "ASIA". If all else fails, ask the front desk.

thanks for taking the time.

It actually depends on where you're going. Different kinds of plugs are used in different countries in Asia. You might need more than one kind of adaptor plug.

Good point by Doug. Some hotels in Thailand and SEA try to discourage people from plugging electrical appliances in their rooms so they purposely use odd, or not the norm for that country, type of plugs. For instance in Thailand the traditional plugs are the round and the almost US type, both prongs are the same size while in the US one is wider than the other. A lot of the older hotels would install a British type sockets in their rooms. A multi adapter can deal with this problem and they are very cheap.

The kit came with 4 different types of adapters...their pretty small so I'll bring all of them that apply along just in case.

Most electronics today are dual voltage, so you don't need a convertor. But you need to check your device to make sure. Its usually on the plug (if its a chunky plug) or on the device itself. It should read INPUT: 110V-220V OR 100V-240V or something similar. If it just say INPUT: 110V or just one number then it won't work.

On a recent trip to Indonesia, I realized that my power cord for my Nintendo DS only took 110v, so I couldn't charge it for the whole trip.

pook, those thais are cheeky!!