Compatible with most wooden train toy sets (like Thomas the Tank Engine). This connector works with my other rail designs. I wanted to allow maximum flexibility in terms of connections, and not have to worry about male-to-male or female-to-female, so I made everything female and added these male-male connectors.

SolidWorks file is for SW2015. STEP file is available if you can't read SW2015 files.

See my other designs for train tracks as well:

Flexi Track - http://www.thingiverse.com/thing:1589228 T Junction - http://www.thingiverse.com/thing:1579594 Equilateral Y Junction - http://www.thingiverse.com/thing:1576147 Cross Junction - http://www.thingiverse.com/thing:1779661