Stem Shield for your Arduino, the Velleman.

The HC-12 433MHz Transceiver is a wireless communication Module, which is based on the RF SI4463 chip, has a built-in microcontroller and can be configured by AT commands, the maximum output power is 100mW (20dBm) and the receiver sensitivity differs from: 117dBm to -100dBm, depending on the transmission speed. Accepts 3.2V - 5.5V and can be used with 3.3V and 5V UART voltage devices.

This is the FeatherWing Adalogger: it adds a real-time clock with battery and micro SD card storage to any Feather mainboard. Using the Headers, you can connect a FeatherWing to the top of your board and let the board fly!

When you assign a high level to the module pin, the electro magnet can suck magnetically conductive objects. Otherwise, it will release the object.

An electro magnet is a type of magnet in which the magnetic field is produced by electric current. An electric current flowing in a wire creates a magnetic field around the wire, due to the Ampere Law. To focus the magnetic field on an electro magnet, the wire is wound into a coil with many twists of wire side by side. The Magnetic Field of All Twists of the Wire passes through the Coil Center, creating a Strong Magnetic Field there.

It's Easy to Use to Learn the Electro Magnet Principle.