Features:

• Surge Tec^® arresters incorporate special features that make them stand above
  other Secondary Arresters and Transient Voltage Surge Suppressors (TVSS).
• These arresters use a patented (#5,502,612) fault withstand design along with
  replacement indication.
• The arresters are available in 175 volt, 480 volt and 650 volt AC ratings for
  application on system voltages below 650 volts phase to ground and operate at
  frequencies between 48 and 62 Hz.
• The units come with 18 inch, #14 AWG solid copper wire leads and are
  designed to be mounted outdoors or indoors.
• FAULT WITHSTAND CAPABILITY - Surge Tec^® secondary arresters' patented
  design achieves a fault withstand capability of 10kA rms without the use of any
  external fusing.  This unique design has been tested at high current failure
  modes to verify its ability to withstand a failure without a violent fracture of its
  housing.  Fault current is the full available current that the device conducts in the
  event it is short circuited by conducting a surge beyond the designed capability.
  This provides significant advantages in the area of secondary voltage protection.
• REPLACEMENT INDICATION - A visual indication on the front label permits
  routine checks of the arrester's operational status.  Indication windows on the
  label turn black if the arrester fails.  The arrester should be replaced when any
  area of any window turns black.   

Application:

• MacLean's Surge Tec^® arresters are classified for category B and C installations
  based on the diagram shown below.
• The arresters are designed for repeated operation and continuous protection.
• Surge arresters provide the path of least resistance to ground for surges on a
  system.  THE ARRESTERS SOULD BE INSTALLED BY A LICENSED
  ELECTRICIAN.
• To provide the best protection, the lead wires should be kept as short as
  possible.  When installed properly, they will divert lightning surges to ground very
  quickly.
• Surge Tec^® arresters offer the first line of defense for the entire electrical service
  and protect wiring, major appliances, pumps, and heating/air conditioning
  equipment.
• For added protection to computers, MacLean Power Systems recommends
  a plug-in-strip type of device with lower clamping voltages as a second line of
  defense. This type of coordination provides excellent surge protection for the
  entire electric service.