Good scope for the money - Vortex Strike Eagle 1-6x24mm Rifle Scope AR-BDC Reticle

For the price, this is an excellent entry level LPVO. I'd lean toward the Primary Arms 1-6x24 gen 3 ACSS for about the same price, though, as it has a better reticle, and similar glass quality and warranty. n Both use a 30mm tube, 24mm objective lens, and work quite well on an AR-15, although the eye relief is a bit limiting compared to higher end HD glass scopes, but those cost considerably more as well.