A shock absorber assembly comprising: a main tube disposed on a center axis and extending between a first end and a second end defining a fluid chamber (28, 30) extending therebetween for containing a working fluid; a main piston slidably disposed in said fluid chamber (28, 30) dividing said fluid chamber into a compression chamber between said main piston and said first end and a rebound chamber being between said main piston and said second end; a piston rod disposed on said center axis and attached to said main piston for moving said main piston in a compression stroke and a rebound stroke; a hydraulic compression stop including an additional piston disposed in said compression chamber adjacent to said main piston and attached to said piston rod for movement with said piston rod during said compression stroke and said rebound stroke to provide additional damping force; said additional piston including a body disposed on said center axis extending from said piston rod to a body end spaced from said first end and defining a conduit extending along said center axis and in fluid communication with said fluid chamber (28, 30); and an actuator disposed in said conduit and attached to said body and being movable from a closed position to an open position during said compression stroke with said open position allowing the working fluid to flow through said actuator and said conduit and said closed position preventing the working fluid from flowing through said actuator and said conduit, wherein said conduit has a cylindrical shape defining a conduit diameter for receiving said actuator, wherein the shock absorber assembly further includes a retainer disposed in said conduit and attached to said body for securing said actuator in said conduit, wherein said retainer defines a hole having a hole diameter (D H) being less than said conduit diameter (D 1) and disposed on said center axis and in fluid communication with said conduit for allowing the working fluid to flow through said retainer and said conduit, wherein said body defines at least one orifice (104, 106) disposed in fluid communication with said body for allowing the working fluid to exit said body, and characterised in that said actuator includes a first spring having a predetermined spring tension disposed in said conduit and a blocking member disposed in said conduit and sandwiched between said spring and said retainer for limiting the flow of the working fluid through said conduit, wherein said blocking member is a disc of circular shape disposed between said spring and said retainer, wherein the shock absorber assembly further includes a second spring disposed in said conduit and extending between said retainer and said disc to sandwich said disc between said first spring and said second spring and space said disc from said retainer. a main tube disposed on a center axis and extending between a first end and a second end defining a fluid chamber (28, 30) extending therebetween for containing a working fluid; a main piston slidably disposed in said fluid chamber (28, 30) dividing said fluid chamber into a compression chamber between said main piston and said first end and a rebound chamber being between said main piston and said second end; a piston rod disposed on said center axis and attached to said main piston for moving said main piston in a compression stroke and a rebound stroke; a hydraulic compression stop including an additional piston disposed in said compression chamber adjacent to said main piston and attached to said piston rod for movement with said piston rod during said compression stroke and said rebound stroke to provide additional damping force; said additional piston including a body disposed on said center axis extending from said piston rod to a body end spaced from said first end and defining a conduit extending along said center axis and in fluid communication with said fluid chamber (28, 30); and an actuator disposed in said conduit and attached to said body and being movable from a closed position to an open position during said compression stroke with said open position allowing the working fluid to flow through said actuator and said conduit and said closed position preventing the working fluid from flowing through said actuator and said conduit, wherein said conduit has a cylindrical shape defining a conduit diameter for receiving said actuator, wherein the shock absorber assembly further includes a retainer disposed in said conduit and attached to said body for securing said actuator in said conduit, wherein said retainer defines a hole having a hole diameter (D H) being less than said conduit diameter (D 1) and disposed on said center axis and in fluid communication with said conduit for allowing the working fluid to flow through said retainer and said conduit, wherein said body defines at least one orifice (104, 106) disposed in fluid communication with said body for allowing the working fluid to exit said body, and characterised in that said actuator includes a first spring having a predetermined spring tension disposed in said conduit and a blocking member disposed in said conduit and sandwiched between said spring and said retainer for limiting the flow of the working fluid through said conduit, wherein said blocking member is a disc of circular shape disposed between said spring and said retainer, wherein the shock absorber assembly further includes a second spring disposed in said conduit and extending between said retainer and said disc to sandwich said disc between said first spring and said second spring and space said disc from said retainer.