This advanced 500 user standalone controller features anti-vandal metal keys for PIN code and/or RFID user credentials. AC-Q42H has a rugged metal construction ideal for installations in high traffic environments. This model comes with removable terminal blocks, for quick installation, and has advanced programming options. Built-in 125 kHz RFID card reader 500 users can have PIN and / or RFID user credentials for granting access. Smooth attractive design, with anti-vandal construction. Highly-visible blue backlit keypad Slim, rugged metal construction (AC-Q42SB) 3 operational Security Levels can be selected with special PIN codes. Supports up to 8-digit PIN codes, with timed wrong code lockout after several wrong attempts. 2 tri-colored LEDs and integral sounder for programming and operation. Wide range of low voltage AC/DC power input.