The M-20 SD is a feature-loaded ergonomic and Double/single-action rimfire pistol. It sports a machined aluminum slide allowing for use of both high velocity and standard velocity ammunition.  Features include slide serrations front and rear hammer de-cocker textured grip and slide-mounted safety. These features combine to make for a smooth and enjoyable shooting experience.  The SD model gets the addition of a threaded barrel for the attachment of muzzle devices. Hello Suppressors. Hello compensators.