the plastic rectangles, and the metal squares use the same chip, have the same number of leds. the only difference is the shape. the metal squares have the 3 led in a triangle shape, where the plastic rectangles are in a straight line. each module of either uses three channels (r,g,b) to turn on all three leds. (if the red signal was sent from a ssc, then all three turn red, etc...) the plastic rectangles are about twice as thick, but i don't know if anybody is putting them behind something they have to worry about thickness.