The UTG OP3 Micro is a compact green dot reflex sight with a 4 MOA dot. It uses the Doctor optic footprint, so it mounts directly on slides, plates and adapters cut for that pattern. A low-profile Picatinny base is included for use on a rifle, shotgun or pistol rail. The housing is machined from 6061-T6 aluminum and finished in matte black anodizing. It is a tough miniature reflex sight at an affordable price. Many shooters find a green dot easier to pick up than red in daylight, and the 4 MOA dot is a good middle ground for close-range speed and mid-range shots. Features: 4 MOA single green dot Doctor footprint Machined from 6061-T6 aluminum Matte black anodized finish Low-profile Picatinny base included Confirm your slide or plate is cut for the Doctor footprint before you order. It does not fit RMR or ACRO cuts without an adapter. After mounting, check that the screws are snug and even, then zero the sight before you rely on it.