I have a battery that is about 80% dry, and when I use it in my LS20, the low engages as usual, but for high, only the GD led engages, and no low. Pretty neat! The GD isn't as bright as it normally is with a full cell, but this made me wonder if an LS20 could somehow be modified so that high doesn't engage the 3mm's, I guess saving some battery life - though I don't know how much - and making it truly two 'independent' stages. Not that it functionally changes the light's behavior much, but thought it would be pretty interesting =)