Feature: Special sealed guide block stops leaking in high pressure. Concave seal prevent oil from leaking.Steel round disk on the back for strength. Cylinder is made of seamless steel pipe. high precisioned grinded.Longer life. Self clean piston parts achieves smooth operation and consistent performance. Easy to install with simple hand tools. Fit for: Fits the following Z4 Years: 2003-2008 2.5i Convertible 2003-2008 3.0i Convertible 2003-2008 M Roadster Convertible 2003-2008 Roadster 3.0i Convertible 2003-2008 Roadster 3.0si Convertible Part Number:51247016186 Colour:black Material:metal Package Contents: 2 x Rear Trunk Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.