Seco-Larm Enforcer Overhead Door Magnetic Contact, Closed Loop (SM-226RQ)

Seco-Larm SM-226RQ ENFORCER Overhead Door-Mount Magnetic Contact, Closed Loop, Adjustable to Fit Most Door-channel Widths, 2-3/4" (70mm) Gap, 24" (61cm) Wire Leads Enclosed in Armored Cable

WESUA Magnetic Switch Alarm Sensor Overhead Garage Door Contacts with L Bracket

Seco-Larm SM-4201-LQ Track-Mount Overhead Door Magnetic Contact Switch, Rugged Aluminum Housing, 36" Wire Leads, for Closed Loop Circuits, 3" Gap, Weatherproof, Mounting Bracket Included