A concealed anti-tamper device to prevent unauthorized opening and tampering with a manufactured product includes a shell, an anti-dismantling structure concealed in the shell, and at least one key. The shell defines a through hole and a slot. The anti-dismantling structure includes anti-dismantling hook module with hook, driving module, and resetting component anti-dismantling hook module. The anti-dismantling hook module is movable within the shell, and when the product is to be locked, the separate key rotates the driving module, which drives the hook of the anti-dismantling hook module to embed in the slot. The key is rotated in the opposite direction to unlock, until the driving module separates from the anti-dismantling hook module, and the resetting component separates the hook from the slot by the restoring force of a spring.

A concealed anti-tamper device to prevent unauthorized opening and tampering with a manufactured product includes a shell, an anti-dismantling structure concealed in the shell, and at least one key. The shell defines a through hole and a slot. The anti-dismantling structure includes anti-dismantling hook module with hook, driving module, and resetting component anti-dismantling hook module. The anti-dismantling hook module is movable within the shell, and when the product is to be locked, the separate key rotates the driving module, which drives the hook of the anti-dismantling hook module to embed in the slot. The key is rotated in the opposite direction to unlock, until the driving module separates from the anti-dismantling hook module, and the resetting component separates the hook from the slot by the restoring force of a spring.

The present invention provides a key blank and a key set. The key blank includes one or more telescopic members inserted through corresponding one or more channels of the key shank for fitting to release a security mechanism of a lock unit. The lock set has one or more fitting keys and a lock unit including: a stator; a rotor; a first locking mechanism; and an additional security mechanism including one or more wafer units. The key shank has one or more telescopic members each inserted in a channel perforated in the key shank. The wafer unit of the security mechanism is located and configured for engaging an edge of the telescopic member when the fitting key is used, such that each telescopic member will move the respective wafer unit it engages for releasing the additional security mechanism for allowing the rotor to rotate in the stator.