Too much $$$ for not enough. - Precision Reflex PRi Low Profile Adjustable Gas Block .625 Diameter

The gas adjustment screw has a simple and small spot of thread lock. With a small amount of use, this can work itself in or out or be lost. For the cost of this, which makes it about in the middle of the pack, I would have expected a better method of controlling gas. If you buy this, add something like blue thread lock to the screw. And, they do not come with a black screw or pin - pin for the gas tube. This makes two silver spots. These are not pictured! Oh the shame.