It is a combination of two slider-crank mechanisms sharing a common green slider.
Input: pink crank.
Output: blue crank. It turns at the same input velocity but in opposite direction.
Input and output are coaxial.
Disadvantages:
- Inertia forces created by reciprocating parts.
- Dead positions (when output crank and its conrod are in line).
The mechanism becomes a regular coupling (no reversing) when the cranks are set to be always parallel.