Super Mica is used to open locked doors by pushing this material in a door jam and shimming the lock lever open by pressing it back in to the door lock. This material is tough enough to wedge into most door jams several times. This method is similar to the old credit card in the door jam method. The only difference is that this material is thinner and more flexalbe then a credit card.This pack of 6 pieces of plastic will open virtually any spring live latchbolt. Once in your hands you will be opening most problem situations. Each piece lasts longer and performs better than anything you've ever seen before. Better than shim steel.