You can use whatever gauges that you like. You'll see famous rockers using everything from super lights to medium or heavy strings. The lighter the string, the easier it is to bend. The heavier the string, the fuller the sound. Different manufacturers label string gauges and put sets together in different ways. Some people use custom gauged sets that fit their preferences. I use Fender light gauge (.009 - .042) on my Strat; they're easy to play and bend easily (I play rock and blues). I have been thinking about changing to Fender regular gauge (.010 - .046) to fatten up my sound a little bit.