Before you run to the store to buy breakers, take a very close look at your breaker box and breakers. There are different types of Siemens breakers that are not interchangeable! (Ask me how I learned that) Best to take out a breaker and take it with you to the store. These different types may look exactly the same on the front, but be very different on the back where they connect. Also see if there is a breaker box 'type' code - write it down and take that with you. BTW, I have a couple of brand new, never used, non-returnable Siemens breakers for sale if anyone in Regina Saskatchewan is interested.
Also, after running around town to four different home centers and realizing the breaker I wanted was a bit unusual and was not stocked by the home centers, I found a wholesale electrical supply house that was willing to sell me the one I wanted for HALF the price of breakers at the home centers.