The Sunwayfoto SSB-02 Index Stop Bar is and Arca-type and RRS compatible stop bar used to mark your no-parallax point or as a safety stop on a rail. It is made from CNC machined aluminum and has a nylon thumb screw that allows for easy adjustment. A satin anodized surface finish resists abrasion and corrosion.  The SSB-02 features a 1/4″-20 mounting point that is useful for mounting accessories.