Vktech 4pcs MAX7219 Dot Matrix Module Control Display Module DIY Kit A single module can be driven by a 8 * 8 common cathode array Module Operating voltage: 5V Module size: Approx.5 x 3.2 x 1.5cmL*W*H) With four fixing screws hole, hole diameter is 3mm Modules with input and output interfaces, supports multiple modules cascade