This kit is 2.6″ outside diameter and 2.0″ inside diameter. The ring is 0.30″ wide. It has 20 LEDs which are wired as 2-in-series with a resistor. Each set is in parallel (10 sets of 2 LEDs).
The PCB is 0.062″ thick, FR-4 epoxy-glass, Plated Thru-Holes, silkscreen on the top layer, and a green solder mask. It will operate from 6v to 12 VDC. The PCB will fit 5mm or 3mm UV LEDs.
It comes as a kit and must be assembled. Includes a 9v battery clip.