Grace Optics M1 Topless Red Dot Sight (3 MOA Reticle)The design of the M1 is built for strength, even though it has an open top design. The glass is very strong and the sidebars make it just as strong as any other site on the market. Topless Design The M1 has a topless design designed to give you a wider field of view, resulting in quicker target acquisition and more accurate shooting. Footprint The M1 uses the SIG Romeo1 footprint and comes with a Picatinny rail mount.