I already have an EOTech 512 on the rifle so I don't need a new holosight.
EOTech's website says their magmifier will work with any of their holosights.
If you have a quick release on your holosight you'll need to use the included 7mm riser that comes with the magnifier, otherwise you won't use the riser.
If my Troy folding sight won't fit beneath the magnifier I'll have to use the riser and add a quick release to my holosight. I don't want to do that.
I'll also be buying wholesale which beats their sale price.