This item is provided by Crutchfield.com and includes free phone technical support for the life of the product. Details on how to take advantage of this service will be included with your package. Should you have any issues locating information on how to contact Crutchfield Technical Support, please contact this website's Customer Service department. This top shelf is made for Solidsteel S4 modular audio racks . It's crafted from thick vibration-dampening MDF (Medium Density Fiberboard). It's also coated with a polymer laminate to further dampen vibrations. What's in the Box: 1. Top shelf (for S4 Series)