[bsmith]

Christine, my LEDs are 5mm so you will require less if using a bogger diameter, your battery will not last quite so long with the brighter output but LEDs take hardly any current so I'm sure they will last a long time anyway.

Gordon, good idea it could be that each alternate one is iluminated to maintain the ring pattern. I doubt very much if this will be anything like as bright as a flash gun\ring flash but I found it delivers a softer more efective light for close macro, and when you move in close if the subject is live, theres no bright sudden flash to scare it off.

Bob