Most manufactures that offer a stop have tweaked things around a bit but they all pretty much accomplish the same thing. I think you could find videos of just about all of the different manufactures particular designs online. Huskemaw, Vortex,Swarovski,Bushnell,Zeiss, Kahles, S&B, leupold, USO, and I'm sure I'm missing a few all offer a Zerostop of some type.