4x4 High Quality Keyboard Matrix Push Buttons 16 Touch Keys

XY-V17B is a smart voice module, integrated IO segment trigger, control UART series, ONE_line control of a single serial bus, MP3 standard and other functions; Supports MP3, WAV format decoding, maximum storage capacity on 32G TF card, update audio files from TF memory card via USB data cable to connect computer.
Voice Module MP3 Player features:

- Support MP3, WAV decoder format.
- Support sample rate ( KHz): 8 / 11.025 / 12/16 / 22.05 / 24/32 / 44.1 / 48.
- 24-bit DAC output, support 90dB dynamic range, support 85dB signal-to-noise ratio.
- Fully compatible with FAT16 / FAT32 file system, 32G TF card with maximum support, 32G U disk support.

GSM A6 Four Band GPRS Module with MCU Antenna features:
- GSM / GPRS module / development board / shield based on GPRS A6
- Supports GSM / Dual band GPRS, available for remote GPRS and SMS data transmission
- Compact size and low current consumption
- With energy saving technique, current consumption is as low as 5mA (sleep mode)
- Communicates with the microcontroller through the UART port, supports the command including GSM 07.07, GSM 07.05 and Ai-Thinker Enhanced AT Commands
- Working frequency: four-band network, 850 / 900/1800 / 1900MHz
- Operating voltage: 4.8-9VDC (Supply power of the on-board regulator circuit for the A6 module)
- Working current: 2A maximum
- Current Sleep: 5mA

NFC RFID Keychain Tag 13.56 MHz features:
- 32 bit unique code
- Protocol: ISO14443
- Compatible with NFC Mifare 1k
- Memory: 1kB EEPROM
- Operating frequency: 13.56MHZ
- Communication speed: 106Kboud
- Reading distance: 2.5-10CM
- Reading time: 1-2MS
- Working temperature: -20ºC to 85ºC
- Number of uses 100,000 times
- Data retention: 10 years
- Material: ABS
- Dimensions 40.5 x 32 x 4.2 mm

It can be used to control the microprocessor of the Arduino AVR PIC system and others, or as a digital potentiometer rotating the rotary encoder can be counted in positive and negative, depending on the direction of rotation; with the button of the rotary encoder can be reset to its initial state, which starts counting from 0.

ESP32-WROOM-32E (ESP32-DEVKITC-32E) is an evaluation board with ESP32 processor, 4MB FLASH, 802.11 a/b/g/n (Wi-Fi, WiFi, WLAN) and BlueTooth® Smart Ready 4.x dual-mode. It is much faster than the ESP8266 processor (NodeMCU and similar), and very easy to use.

433.92 MHz radio receiver module that allows you to also control it via a radio remote control. You can control each channel either by remote control, the free APP "eWeLink" or with wizards such as Alexa or Google Home. This will allow you to create scenes, schedules, and much more. Its relay supports up to 4 devices simultaneously. Each device can be powered by 5-24 V DC.

Voltage Sensor Module 0.02445V ~ 25V.
When the module is powered by 5V voltage detection It does not exceed 25V, and when the module is powered with 3.3V the voltage detection does not exceed 16.5V.
100% Compatible with Arduino.
DC voltage sensor 0-25v for Arduino features:

- Input voltage: 0-25 VDC
- Voltage detection range: 0.02445V-25 VDC
- Analog voltage resolution: 0.00489 V
- DC input connector: cathode terminal connected to VCC, GND negative pole
- Output interface: "+" then 5 / 3.3V, "-" then GND, "s" then the Arduino AD pins

This little board is great for any type of prototyping - enables troubleshooting and debugging of any board with voltage from 0 to 5.5V. The  board interprets the commands and sends them further via a proper protocol (ranging from UART through I2C up to HDD44780 LCD). The Pirate lets analyze as well the data sent back from the device to the computer terminal effectively allowing to decipher potential errors. The bootloader installed on the board enables the quick and easy update of firmware and changing the functionality of the board.

This board features PIC24FJ64 and FT232RL USB-to-serial chip enabling swift communication over the mini-B USB port. On the other end of the board 2x5 pin header is placed with detailed descriptions of each pin.

TDA2030A 1X18W Audio Amplifier features:
- Chip: TDA2030A
- Power supply: DC 6V ~ 12V
- Channel type: Single channel - Output power: 1 x 18 W
- Output output: 4 ~ 8 Ohm
- Mono mode
- Size (LxWxH): 31.6 x 23.5 mm

3.5mm Audio Jack Breakout Headphone Video Audio MP3 Jack Module. This female jack connector adapter 3.5mm audio soldered on a PCB board, it is ideal to use in our projects. TRRS connectors are the audio-style connectors seen on some phones, MP3 players and development boards. TRRS stands for "Tip, Ring, Ring, Sleeve", reflecting the fact that unlike a standard stereo connector, this one actually has three conductors and a ground.