Barrel-shaped head b of link 3 fits into and slides along oval guides a, of round cross section, in link 1. Round guide pin c of link 2 fits into a hole in the head of link 3. With respect to each other, links 1 and 2 accomplish three turning motions about three perpendicular axes x-x, y-y and z-z, and two translational motions along perpendicular axes x-x and z-z.
$119$EM,MJ$