Once you have your FasTrak transponder, simply mount it on the inside of your windshield and you’re good to go! When driving on the South Bay Expressway, just continue through the non-stop “FasTrak Only” lanes and your toll will be automatically deducted from your prepaid account. It’s that easy! You can check your FasTrak account balance on our Web site any time 24/7. And don’t forget to take your transponder with you when you travel to Orange County or the Bay Area. You can use your FasTrak transponder on any California toll facility that accepts FasTrak. Click here to see where FasTrak can take you!