Our Frenzy-X has 2 types of footprint, TEK and MOJ.Our Frenzy-S has 1 type of footprint, MAG.TEK footprint is same with Docter, Vortex Venom/Viper, Burris Fastfire.MOJ footprint is same with Trjicon RMR.MAG footprint is same with Shield.If you have any questions about this, welcome to contact us. we can help you choose.