Abstract: A keyway plug that provides a means for preventing the correct key from opening a tumbler lock, including a plug and an extractor. The plug fits into the keyway to block complete insertion of a key. An arm extends from the tip of the plug across the tumblers, but is short enough so that the outermost tumbler drops to hide the plug. The extractor includes a narrow finger, the end of which pushes the innermost part of the plug upwardly, while the tumblers push the outermost part of the plug downwardly. A chamfer at the outer end of the plug arm pushes the outermost tumbler up out of the way so the plug can be removed. The upper edge of the finger includes a hook that mates with a matching notch in the lower edge of the plug arm. As the extractor is removed, the hooks and notch interlock, pulling the plug from the keyway.

Abstract: A keyway plug that provides a device for preventing the correct key from opening a double-sided tumbler lock, including a plug and an extractor. The plug fits into the keyway to block complete insertion of a key. In one embodiment, a pair of arms extend from the tip of the plug across both rows of tumblers, but is short enough so that the outermost tumblers drop to hide the plug. In the second plug embodiment, the outermost tumblers drops into a notch in the arms to prevent the plug from going too far into the keyway. Alternatively, only one arm has a notch. The extractor includes a narrow finger, each edge of which include a hook that mates with a matching hook in the inner edge of each plug arm. As the extractor is removed, the hooks interlock, causing the plug to be removed.

Abstract: A keyway plug that provides a means for preventing the correct key from opening a tumbler lock, including a plug and an extractor. The plug fits into the keyway to block complete insertion of a key. In one embodiment, an arm extends from the tip of the plug across the tumblers, but is short enough so that the outermost tumbler drops to hide the plug. In the second plug embodiment, the outermost tumbler drops into a notch to prevent the plug from going too far into the keyway. The extractor includes a narrow finger, the upper edge of which includes a hook that mates with a matching hook in the lower edge of the plug arm. As the extractor is removed, the hooks interlock, causing the plug to be removed.