I just bought another green pen ebay cheapy. I put regular heavy duty AAAs one measuring at 1.5v and the other at 1.6v. This pen was weak small dot and just about no beam in darkness, also if this makes a difference it has the pressed and glue in type of modules that in my experience dont seem to be very strong, I thought then this is the perfect gift to send to my brother in law as his first new green pointer for presentations at work. I just had the box and everything ready to ship. At the last sec I put in fresh alkaline batterys and I was amazed. This pen popped a balloon! I cant strees what a difference that alkaline batterys make. By the way this like my 3rd ebay pen that can pop a balloon. This gift could of been a catastrophy as I was planning on putting a note saying it was no stronger than a red cheapie pointer. Phew!:thinking: