I purchased the React 5 pin a little over a year ago but I just couldn't make it work for me. The problem was that the sight housing is a really big 2.125" inside diameter and a 2.312" outside diameter. I just could not get the housing centered around my peep when at full draw. I had to float the sight around until I felt it was centered with the peep the then I could focus in on the pins.
Note: I do use a 1/4" diameter peep, which is a Specialty Archery verifier.
On Friday, I received via ups, the React One, which has a much smaller housing, which is 1.650" inside diameter and a 1.875" outside diameter. Now I can see the entire housing just at the outer edge of my peep.
But now I have a new problem. When I mount my Tight Spot quiver, it gets in the way of sight adjustment knob. With the React One, you need to have access to the knob to rotate the knob when switching between the 9 different yardage markings. I will have to make a new bracket for the Tight Spot quiver. I'm a master machinist and work in a R&D machine shop, so this will not be too difficult.