If you are really concerned about having your card skimmed, you can take any simple magnet and erase/scramble the data by waving it over the mag tape.
You can check that things worked by swiping before and after at some place where they'll let you swipe (or by making/buying a reader).
If you are really concerned about having your card skimmed, you can take any simple magnet and erase/scramble the data by waving it over the mag tape.
You can check that things worked by swiping before and after at some place where they'll let you swipe (or by making/buying a reader).