STI 3331 Wireless Doorbell Extender Sensor

Make sure every entry alert is heard, even in distant or noisy areas. The Safety Technology International STI 3331 Wireless Doorbell Extender Sensor converts your existing hard-wired doorbell signal into a long-range wireless chime, extending audible notifications up to 500 feet line-of-sight. With two selectable sounds and adjustable output from 64 to 81 dB, the STI-3331 is flexible enough for offices, warehouses, monitoring stations, and security checkpoints.

Designed for easy installation with traditional doorbell wiring, the unit lets facility managers and security integrators add remote chimes without extensive rewiring. Because it pairs with an STI receiver (sold separately), you can scale coverage and integrate into broader security and surveillance workflows. The low-profile white housing blends into professional environments while providing dependable audible alerts for staff and visitors.

For reliable door notification in commercial and security-conscious settings, add the STI 3331 Wireless Doorbell Extender Sensor to your monitoring setup — order now or contact your Safety Technology International representative to discuss integration options.

• Extends existing hard-wired doorbells to hard-to-hear areas for reliable visitor notification
• Up to 500 ft line-of-sight wireless range keeps remote rooms and workspaces informed
• Two selectable chime sounds and adjustable volume (64–81 dB) to suit commercial environments
• Simple integration with traditional doorbell wiring—no major rewiring required (STI receiver required)
• Ideal for security, surveillance, and monitoring applications where timely audible alerts matter