AstroSystems Secondary DewGuard 2
AstroSystems amazing Dew Guard secondary heating system attaches directly to your secondary mirror and then automatically senses the air temperature and the mirror temperature, then maintains the secondary mirror at a preset (adjustable) temperature above the ambient air temperature. It gently warms the secondary with 2-4 watts when on full and has 4-8 evenly spaced contact points for optimum thermal distribution. Uses any external 12 volt dc supply or you can run on a 9v battery in a pinch. No more heat ropes!
1.5"-2.4" minor axis
2 watt max