Description: This version of the LED backpack is designed for two dual 14-segment "Alphanumeric" displays. These 14-segment displays normally require 18 pins (4 'characters' and 14 total segments each) . This backpack solves the annoyance of using 18 pins or a bunch of chips by having an I2C constant-current matrix controller sit neatly on the back of the PCB. The controller chip takes care of everything, drawing all the LEDs in the background. Specification: Selling Points: LED display I2C control 2 - line control. Size: approx. 50.7 x 28.4 x 12.4mm / 1.99 x 1.12 x 0.49inch Package Includes: 4 Piece Digital Tube LED Display Module Note: Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid. Photo color might be a little different from the actual product due to color display of different monitors. Thanks for your understanding and enjoy your shopping moment.