The Model 16-1-X-X protects equipment from Over, Under, Over/Under voltage or rapid cycling conditions that can damage valuable equipment. Trip and restart delays are adjustable, or can be disabled. Input voltage ranges are 12-30 VAC/VDC or 30-277 VAC/VDC. The 8-pin plug-in has 2 SPDT relays, while the surface mount case has 1 SPDT relay.