The REX T1 riser mount is a low profile, lightweight, T1 mount for AR platforms. Set at the ideal height for an absolute co-witness or lower 1/3 utilizing an additional spacer. The T1 mount is versatile while providing shooters with an excellent option for all T1 compatible optics. With its modular design, you are able to mount your optics at your preferred heights. Features: Low profile rail riser Lightweight, 2.3 oz total installed co-witness height Lower 1/3 co-witness Absolute co-witness