Stem Shield for your Arduino, the Velleman.

The RFID USB Reader is a simple to use, USB to serial base unit for the ID-3LA, ID-12LA, and ID-20LA readers. 

The MFRC522 operates in the frequency range of 13.56 MHz and uses the principle of modulation and demodulation to interact with the RF proximity card. This unit can perform the function of the card reading and writing device, to identify and record various information on the card, to encode and authorize an RF card.

Módulo 433MHZ LORA com alcance 3000m.

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.