Magnetic contact sensor D-20B — brown, door/window security reed switch

Magnetic contact D-20B — brown, door/window security reed switch is a compact two-part sensor designed to detect opening and closing of doors and windows. The assembly includes a fixed sensor element and a separate magnet; when aligned and close together the internal reed contacts remain closed, and when separated they open, generating a contact change that can be read by alarm panels or monitoring devices. The brown housing and low-profile design make the device suitable for visible wooden or dark-framed doors and windows, while its surface-mount format supports simple DIY or professional installation without recessing.

Advantages

The magnetic contact offers a simple, low-power switching function with reliable mechanical operation and minimal maintenance. Its surface-mount construction allows quick installation on a variety of frame and sash materials, and the brown finish reduces visual contrast on dark surfaces. The device is compatible with common alarm panels and wired security circuits, providing a straightforward input for perimeter intrusion detection and status monitoring.

Suitable for

• Home and apartment door/window perimeter security
• Small business and office entrance monitoring
• DIY alarm and automation projects
• Status detection for cabinets, gates and shutters

Key specifications

• Type: Reed switch magnetic contact with separate magnet
• Mounting: Surface-mountable design for frame and sash attachment
• Color: Brown housing to match dark frames
• Operation: Normally-closed contact that opens when magnet is moved away
• Power: Passive mechanical contact — no internal power required
• Compatibility: Wired alarm panels and monitoring inputs supporting dry contacts
• Size: Compact, low-profile form factor for minimal visual impact

How to use

Mount the sensor body on the fixed frame and the magnet on the moving part (door or window sash) so that when the door or window is closed the two parts align and the contact remains in its resting state. Connect the sensor leads to the alarm panel or monitoring device input configured for a dry contact. Verify correct operation by opening and closing the door or window while observing the zone status on the control panel. Use the brown magnet and sensor pair where the color match improves aesthetics or reduces visibility.

Usage recommendations

Install on clean, dry surfaces and ensure the magnet and sensor faces align within the manufacturer’s recommended gap for reliable operation. Avoid mounting near strong magnetic fields or sources of mechanical impact. For outdoor or high-moisture environments, use appropriate sealing or select components rated for ambient conditions. Test the contact after installation and periodically as part of routine system checks.