Buslink's chip encrypted key matches a chip on the motherboard. Removal of the key prevents unauthorized access to the hard drive. Unlike password, fingerprint or other "security" approaches, removal of the case and connecting directly to the PC bus continues to prevent access to the drive contents. Units are supplied with two keys and registration is required for key duplication. Buslink Cipher Shield drive is available in 500 GB (3.5") size with 128 Bit Encryption. All Buslink drives are housed in a stackable metal alloy case which dissipates heat and are pre-formatted for 100% quality control and convenience to the user.