1. Aluminum alloy case , more to use. 2. There are lot of exhaust holes on the top and bottom of case , help for better heat dissipation. 3. Support installing the cooling fan on the cover , need not worry about the over heating. 4. Add the hanging bracket holes on the case , easy to mounting on other devices or position. Introduction: This is the aluminum case for 4B. It can fix on the devies by bracket, which fit for more using situation. Compatible with:For 4 Model B NOTE:Not included for 4B. Color:Black Material:Aluminum Alloy Package Contents: 1 * Aluminum Alloy Case (Self-assembly required) 1 * cooling fan 1 * Screwdriver(The colors and styles are random, and the designation is not accepted) 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.