The MP135 / MP503 Gas Sensor is a compact metal-oxide semiconductor sensor designed for air-quality monitoring and gas detection, with good sensitivity to methane. It features fast response and recovery, low power consumption, good stability, strong anti-interference capability, and long service life. The sensor’s conductivity changes with gas concentration, allowing a simple external circuit or microcontroller to measure the variation. It is suitable for Arduino, IoT, gas detection, environmental monitoring, and DIY electronics projects.

The Hall Effect Counter Sensor Module is a compact magnetic detection module based on the 3144E Hall Effect sensor and LM393 comparator. It detects magnets and magnetic-field changes and provides a clean digital HIGH/LOW output, making it ideal for motor speed measurement, wheel rotation, object counting, and position detection. It operates from 3.3V–5V DC, includes power and signal LEDs, and features M3 mounting holes for easy installation. Suitable for Arduino, robotics, automation, and DIY electronics projects.