Replaces the stock chassis brace and allows the mounting of a 25mm fan. Best used with JConcepts Finnisher body or similar with raised back section. To use with the stock body you will need to cut a section for the fan to protrude through the body slightly. ** 3/11/15** Made a small update. Decreased the fan mount hole sizes to 2mm so you have the option of using smaller screws through the fans and added a little material to the area above the battery brace slot.