[Ol' Bob]

I've used some RadioShack 500mcd 660nm reds that are 2.2V. They are good up to maximum 3V reverse voltage and worked great with a 2025 3V battery. The Archer Cat. No. of the LEDs is 276-088. These came with red lenses made to pop into a 11/32 hole. I removed the red lenses and the center tab from the black bases from three of them and simply pinched the conecters down to fit right over the battery. The only problem I've had is maintaining good connections at the low current. Clear packing tape worked great.