An electrical transformer is a device which either changes the voltage up or pushes it down to a desired value. In the US, the voltage pushed across the plug points is an 110v compared to many parts of the world where the voltage is 220v. If you own devices such as a mobile phone, or a laptop, they will not work if you travel to US and try their power outlets. If you try to use an outlet which is rated with a higher voltage, you will end up damaging your electrical goods and also might get electrocuted.
220v to 110v converter
The solution of your problem is a voltage converter which will lower the 220v to 110v and do it efficiently over a long period of constant use. If you are going to buy a voltage converter, you ought to be careful about a few things. The material of construction of the 220 to 110 converter should be of very high quality to ensure long lasting use. Also, the electrical cord has to be of high quality construction and preferably of industrial grade strength to prevent electrical hazards. Make sure that you buy a voltage converter which offers ample wattage to all your devices.
Buying it cheap
While there are many places where you can buy a voltage converter, but buying a 220 to 110 converter from an online store will probably be a very good idea. The range of voltage converters available in a well known and reputed online store will be huge compared to a shop which simply might not have the place to stock all the brands available in the market. They also will be able to offer a cheaper price on their products so that you can save some money.