I am very pleased with the quality and ease of use. I ordered the 557 w/ 3X magnifier, but it was on backorder so they offered the 4X magnifier as an alternative. My only complaint is that the 4X does not come with the flip to side mount, otherwise this is a great product for a great price that is of very high quality compared to other holographic sights I have had in the past.
Pros: easy to use and setup, very high quality
Cons: no flip to side mount
This review was written in the old system and had content requirements that are different than reviews written today.