Double Rocker Mechanism is a four-bar mechanism. In this linkage, both the links pivoted to the fixed link oscillate.
It is a Grashof linkage for which the sum of the lengths of the shortest link and the largest link is less than the sum of the lengths of the other two links.
s + l < p + q
s = length of the shortest link
l = length of the largest link
p and q = lengths of the other two links
In Double Rocker linkage, the shortest link is the coupler. It makes a full revolution. The position of the other three links does not affect the nature of the mechanism.
This mechanism is also known as Rocker rocker mechanism and Double lever mechanism.