The 4-Pack includes all 4 board currently available: the MOTHERBOARD, DIGITISER, SENSOR ARRAY and RGB MATRIX. With these 4 boards you have 2 forms of display output: the 4 digit seven segment display of the DIGITISER and the 16 RGB LEDs of the RGB MATRIX. The MOTHERBOARD has a built in real time clock module that keeps time even when unplugged. The DIGITISER can display 4 digits or characters and includes 2 buttons and a potentiometer to let you control what’s being displayed, or the brightness of the display. The SENSOR ARRAY can read temperature, relative humidity, sound and light, with an SD card slot for data recording. The RGB MATRIX has 16 RGB LEDs that are controlled through shift registers, so only use 3 or 4 pins of the MOTHERBOARD. There’s a lot to learn from these kits, so check out each of the boards dedicated pages for more info.