The HS510C Open Reflex Circle Dot Sight has an open frame for a wide sight picture. It is powered by solar cell under normal usage, and a back-up battery to supplement power requirements in low light conditions. The reticle can be switched between a 65 MOA circle with 2 MOA dot, a 2 MOA dot only, or a 65 MOA ring only at the push of a button. Better yet, the same LED projects both reticles, so no re-zeroing is necessary. Features • Parallax free with unlimited eye relief.• New advanced technology LED allows up to 50,000 hours of operation on one CR2032 battery• 2 MOA dot and a 65 MOA ring• Dot only, Ring only, or Dot and Ring reticle combinations• Unlimited field of view• Titanium-alloyed, shock resistant hood• Powered by both battery and solar• QD integrated PHYSICAL SPECS Window Size 20 mm Diameter Dimension (in) 2.73 × 1.53 × 1.61 Weight (oz) 3.74 MECHANICAL SPECS Housing Material 7075 T6 Aluminum Surface Finish Hard Anodize Adjustment per Click 0.5 MOA W & E Travel Range ±50 MOA ENVIRONMENT SPECS Storage Temperature -40℃ ~ 70℃ Working Temperature -30℃ ~ 60℃ Submersion IPX8 Vibration 1000G