So I have down to Operator and Pro Operator. Was reading their FAQ website and got : What is the difference between the Classic and Pro (and difference between Operator and Pro Operator) sights for Glocks? The Classic and Pro Series both use a .140" wide front (item GL-112) The Operator and Pro Operator both use a .125" wide front (item GL-112T) The Pro and Pro Operator rear sight notch is .180" wide Classic and Operator rear sight notch is .150" wide The Pro and Pro Operator rear is longer, extending back toward the end of the slide The Pro and Pro Operator rear face is undercut a few degrees, eliminating glare The Classic and Operator rear sight is better suited for catching on a belt to rack slide (one hand) All models discussed in this Answer are installed using the GTool2 (or a factory sight tool) Seems to me that the Original operators will have less space to let light in when lining up sights, and the Pro Operators will let in a lot of light. What's the difference? Also I see that all Pro series version rear sights extend to the back of the slide. Any benefits to this? I see none. I'm leaning towards the regular operators in green/yellow combo.