Model 8512-20993, this is known as an “Oklahoma Special”, a terminal block is specifically designed to ensure the magnet withstand the electrical storms that are common in the Oklahoma region. This maglock has become a standard install in most commercial buildings, casinos, and other facilities in the State of Oklahoma, not only for the ease of installation, but also for the electronic protection from the special terminal block and the proven durability of this reliable model to stand up to the harsh electrical storms in the area Technical Specifications: Easy installation with keyhole mounting “slides left to right” Dual voltage 12/24 VDC field selectable Built-in MOV spike and surge protection No residual magnetism Specially designed terminal block to withstand electrical storms Housing: attractive, heavy duty anodized extruded aluminum housing