I use mostly AA version of the EOTEch, I put lithium in them. I never had a probolem with heat an d cold but mostly extreme heat but you know about cold in California, so the coldest I encounter was in Big Bear during a winter storm last year. it was cold but no Montana COLD.
Fly Low, And Avoid The Radar.
Chen Lee CL Tactical www.CLTactical.com 909-966-5020