So, what is the difference between the XPS3 and the EOTECH EXPS3? Well, the biggest difference is simply the height at which both of them sit once you add them to a rifle. The EXPS3 has a built-in QD attachment system lever. And what this does is this puts the entire height of the optic at a lower-third height. So it'll put your iron sights in the bottom window of the optic itself, which is preferable, especially if you have a fixed front sight post, and that's what makes this one the most popular. It also has the night vision setting here. And no, it does not actually turn the optic into a predatoresque night vision optic. It simply dims the reticle instantly to a brightness that is very crisp under night vision. In fact, this is probably the best optic for passive aiming with the crispest reticle under night vision, if you're running a PVS-14 , dual-tubes, whatever.
The XPS3 is similar. It has the night vision setting right here that does the exact same thing. But this is actually going to sit on the gun, obviously lower, at a absolute co-witness height. It comes with a standard hex key attachment, little screw thingy, but you can actually swap that out with the thumbscrew that it includes, which I would recommend, as you are then able to tighten and loosen with your fingers instead of having to use a tool. So as you can see right here, we have a LA-5 at the end of this MK18. This optic is going to see over there a little bit. It'll put a little bit of the laser in the field of view. With this optic, it's a little bit more that you're going to end up seeing. So that's the height that it sits at.
And the question is, well, why would I want an XPS3 when I can buy an EXPS3? Well, the answer is: On certain guns, like G3s or other weapons where the receiver is a little bit higher in relation to the stock, or even on MP5s, it can be a little nicer to have an object that sits a little lower. That gives you a little bit more chin on the gun. So I like putting these on MP5s. I like putting them on G3s, even FALs, because it just helps a little bit is in regards to getting a little bit more chin on the gun. Plus they're available usually a little bit more because these are so popular, but ultimately both optics do the same thing. They have the same reticle and they're pretty awesome.