This is the HC-SR04 ultrasonic ranging sensor. This economical sensor provides 2cm to 400cm of non-contact measurement

• Stable performance, accurate measurement range
• Using IO trigger for at least 10us high level signal
• Automatically send 8 40KHz, and detect whether there is a signal to return

• Clean and iconic designed T-shirt, with #POWERTOTHEMAKERS slogan printed on the back, SainSmart cool boy logo printed on the front.
• Short sleeve pullover must-have summer shirt.
• Made of cotton.
• Two Style for you to choose: Logo and Splash.

This board is mostly based on Adrian's Pololu_Electronics and work by Tonok. It is compatible with A4988 and 8825 driver.

• Supports 12V-24V power input
• Compatible with Marlin software

The Sain Smart Nano for Arduino is a surface mount breadboard embedded version with integrated USB. It is a smallest, complete, and breadboard friendly.

• Automatic reset during program download
• Power OK, blue LED, Green (TX), red (RX) and orange (L) LED Auto sensing/switching power input
• Small mini-B USB for programming
• Serial monitor ICSP header for direct program download
• Standard 0.1" spacing DIP (breadboard friendly)
• Manual reset switch Power: The Nano can be powered via the mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.

This is Mega 2560 with 16x2 LCD Keypad module bundle

• The SainSmart Mega2560 R3 has 1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
• SainSmart 16x2 LCD Keypad module has blue backlight with white words, adjustable backlighting. 4 Bit LCD Library for Arduino.

MF RC522 is applied to the highly integrated read and write 13.56MHz contactless communication card chip,

• Easy to use, non contact card reader module
• This module can be directly loaded into the various reader molds
• Working current :13-26mA/DC 3.3V

Excellent industrial design-the same anodised aluminium casing as iPad, which is not only beautiful and tasteful but also greatly enhanced the hardness of aluminum alloy surface, and has good heat resistance and strong wearability.

• Cost-effectiveness; Excellent industrial design.
• Dimensions (mm):205(L) x120(W) x35(H), be carried easily.
• One computer can connect many DSO, extend channel easily.
• Labview\VB\VC\Delphi\C++Builder Second Design instance.