Abstract: A releasable connecting pin for a shackle or the like comprises a pin (45) having a cylindrical body (46) with a head (47) at one end and a boss (48) at the other end. The boss comprises a cylindrical neck (49) and spaced radially extending projections (50a, 50b, 50c) in the form of a male coupling element. A female coupling element comprises apertured flange plates (51, 52) having apertures (53) of a shape complementary to the cross sectional shape of the boss (48) through the projections (50a, 50b, 50c) to permit the flange plates (51, 52) to slide over the boss (48). One flange plate (51) is rotatable about the neck (49) to misalign the boss projections (50a, 50b, 50c) with corresponding notches in the aperture (53) to engage the flange plate (51) behind the boss (48). Set screws 58 extend through aligned apertures (54, 55) in the flange plates (51, 52) to prevent relative rotation and disengagement from the boss (48).