The Elecrow Crowtail – Magnetic Switch is a compact, rugged SPST (single‑pole, single‑throw) reed‑type magnetic sensor module designed for proximity, security, and detection applications. Using an encapsulated dry reed switch (MKA14103) with normally open ruthenium contacts, it closes its circuit when exposed to a strong enough magnetic field—such as from a permanent magnet or solenoid—allowing you to detect door/window closure, level changes, flow passage, or counting pulses. This module offers a Crowtail‑compatible interface, meaning you can plug it into Crowtail base shields or compatible microcontroller boards with ease and minimal wiring. It operates reliably at standard 5V working voltage, with minimal standby current, making it suitable for battery‑powered or low‑power systems. The module is rated for switching up to 10 W power and can switch currents up to 0.5 A DC; its switched AC voltage rating is up to around 140 Vrms. The contact resistance is very low (<200 mΩ), ensuring good signal integrity, and high insulation resistance (>10⁶ MΩ) when open, offering safety and minimal leakage. With an operating temperature spanning from ‑40 °C to +125 °C, this module can function in harsh environmental conditions. The sensor’s compact form (≈28×20×6.8 mm) makes it easy to integrate into enclosures or doors/windows. It’s ideal for DIY home security, object detection, flow or level sensing, and any project where you want a switch triggered purely by proximity to a magnet.