Neopixel
Dimensions: 0.4" x 0.5" x 0.1" / 10.2mm x 12.7mm x 2.5mm
0.5" (12.5mm) diameter circle PCB, 0.1" (2.5mm) total thickness
800 KHz speed protocol
Chainable design
5-9VDC power (can run at 3.5V but color will be dimmed), constant current 18.5mA per LED (~55mA max total per pixel)