A 2D render of the top/front of a small round black PCB. There are 55 sets of copper pads for LEDs, and four tiny semi-circular cutouts around the circumference of the circle. The cutouts are labeled I, O, +, and -.
https://cdn.masto.host/ledssocial/media_attachments/files/112/072/590/906/232/033/original/c87be01915b49c09.png