From the Opalec website:
"*The maximum voltage capability of the NewBeam has changed. We now build the NewBeam with either of two control circuits, which have different voltage ranges. One version will operate up to 8-9 Volts, although the LED current regulation begins to degrade above about 6 Volts. The other version only operates up to a little over 5 Volts, and then draws excessive current above about 6 Volts and will be damaged. You can tell the two apart by looking with a magnifier at the parts under the clear epoxy. If you see a rectangular silver colored part labeled "1B", you have the version which works above 5 volts. If you do not see this part, you have the lower voltage version. Again please be aware that we do not encourage use of the NewBeam above the standard 2 x 1.5 volts."
Bob