The AL-CL4W-12 series are high performance 3-stage weatherproof protectors that provide superior protection of differential or common mode lines from transients and surges. These units will protect up to four 4-20 mA circuits.The first stage is comprised of a differential gas discharge tube. Stage two is a pair of current limiting series resistors and the final stage is a low capacitance diode array. The use of three terminal differential gas discharge tubes provides superior common and differential mode protection against conducted transients versus the use of lower cost two terminal tubes. The second stage series resistance limits the power dissipation of the fast diode clamp array in the third stage. This allows time for the slower but higher power gas tubes to flash over. The diode array clamps the leading edge of fast transients to safe levels until the high power gas tubes turn on. This eliminates the damaging leading edge spike that single stage gas tube protectors let leak through. The diode array's low capacitance assures that the suppressor will not degrade the high-speed signals. The 3-stage design can handle higher-level transients than a protector that uses only diodes.For mounting to masts up to 2 inches in diameter, the HGX-PMT25 mast mounting kit is available (sold separately).For additional information and complete specifications, see data sheet below.