This is a model of a Traxxas rod end, with a swiveling spherical ball insert. It gets screwed onto the ends of tie rods to allow an adjustable mechanical link between two points, often times with a servo at one end. The bore accepts a 3mm screw or tie rod. The bearing end also accepts a 3mm screw or bolt. It is a model of: Traxxas part # 2742X It is actually two separate pieces with .003" clearance between the ball and housing at 1-1 scaling. This gap is purposely more than the real one would have in hopes it might be an actual printable working bearing with the right settings/scaling.