Timothy, it is another Budget Optic. Although in the same price range, Lucid makes quality optics as well as Holosun : budsgunshop.com/product_info.php/products_id/714020810/lucid+litl+mo+micro+red+dot+sight ------------------------- budsgunshop.com/product_info.php/products_id/128942/holosun+he+407c-x2+1x+2+moa+green+dot+black+hardcoat+anodized

Few more holosun options in stock here.
507 is more reticle options, K series are micro rds for small guns, T series are titanium housing, and 509 series are fully enclosed, this helps keep the emitter (where the dot is projected from) clean and unobstructed, in case it gets dropped in mud or whatever.
budsgunshop.com/search.php/other/in_stock/q/holosun+507c

Ameriglo makes good iron sights, but they are mostly unproven in the reddot game, for about $15 more you can get a holosun 407C which is a proven performer, they are feature rich, durable reliable and have a good name in the optics world. The 407C is just like the 507C but it only has one reticle option (a 2 moa dot) while the 507C has 3 different reticle you can cycle through. They both have 50,000 battery life, solar back up, IPX8 water proof rating, both made of 7075 T6 Aluminum, feature auto off (to conserve battery) and shake awake, so its good to go when you need it. There are other brands but for the price Holosun can't be beat. 407C in stock here.
budsgunshop.com/product_info.php/products_id/128937/holosun+hs+407c-x2+1x+2+moa+red+dot+black+hardcoat+anodized />