16x8 1.2" LED Matrix + Backpack - Ultra Bright Square Green LEDs Shipping:2-4 Weeks M2 T 256 (I²C): soldered

M2 T 256 (I²C): soldered headers

this would be the 3

The interface of this sensor uses DFRobot Gravity Interface

In Mass Storage mode it created new drive on your computer and when you drag and drop the HEX file to this drive it program it in the target AVR attached to the ICSP connector

Built in USB means you plug it in to program it

16x8 1.2" LED Matrix + Backpack - Ultra Bright Square Green LEDs Shipping:2-4 Weeks M2 T 256 (I²C): solderedWhat's better than a single LED? Lots of LEDs! And what's better than lots of LEDs? TWO TIMES AS MANY LEDS!!! With the 16x8 LED Matrix Backpack we've doubled your project's matrix capacity by making it super easy to get two separate 8x8 matrices onto one handy board! Matrices like these are 'multiplexed' so to control 64 LEDs you need 16 pins and to control 128 LEDs, you'd need 24 pins. That's a lot of pins, and there are driver chips like the MAX7219