The Warne Aimpoint T1 modular mount was designed to offer easy height adjustments between absolute and lower 1/3 co-witness in one package to fit all T1/T2 interface red dot optics. All riser mounts that we offer share a robust mounting base while the top is engineered specifically for different red dot styles. - Height w/o insert Absolute Co-Witness - Height w/insert lower 1/3rd Co-Witness - T1-T2 type interface - Fits the T1-T2 H1-H2 Crossfire Romeo 5 Red Dot and Holosun 403 503 515 530 - All risers include a .180 thick spacer - Designed and MADE IN USA