Transformers are the key component to any 12 volt – low voltage lighting system. A transformer converts the 120 Volt – line voltage current down to 12 volts. Some transformers have a multiple tap capability, which gives the user the ability to extend range by tapping into a 13, 14, or 15-volt system. Exterior Stainless Steel Transformers commonly have a Lifetime warrantee. A transformer is typically sized by its voltage use. Sizes range from 75 watts to 1000 watts.