A damping unit, such as a shock absorber, includes a cylinder (2), a piston (4) dividing the cylinder into a compression chamber 6 and a rebound chamber (8), and a piston rod (10). The rod extends from the piston through at least the rebound chamber. The compression chamber reduces in volume and the rebound chamber increases in volume as the damping unit contracts generating a compression flow across the piston, and the rebound chamber reduces in volume and the compression chamber increases in volume as the damping unit extends, generating a rebound flow across the piston. The piston has a compression chamber piston face and an annular rebound chamber piston face. At least one rebound restriction is provided in or on the piston, such as one or more rebound ports (26)/passages/valving (28), and at least one compression restriction, such as one or more compression ports 14/passages/valving (20) is provided in or on the piston. The rod has at least one channel (36) in an outer surface of the rod extending along
