This is a great red dot for backup or possibly primary sight - Vortex Razor Reflex Red Dot Sight

I now have three of these. This is a very easy to use, clear re-dot that I can still shoot more accurate tan 3MOA even though the dot covers 3MOA (not easy to explain, but it is plenty accurate to 100+ yards). I use these as backup sights at 45 degrees for close shots when my primary scope is cranked up to high power.

Easy to install, especially when used with the Vortex 45 degree mount made specifically for this scope. Easy to change batteries. Relatively easy to adjust as long s you keep the 2.5mm allen wrench handy.