Edelbrock Part 15806 Belt Tensioner brace is intended for use on 2005 - 10 Mustangs, 2004 - 10 F - 150 trucks and 2007 - 13 Ford SUVs with an aftermarket supercharger installed. The stock belt tensioner is made of cast aluminum and has been known to bend or break under extreme conditions. The Edelbrock steel Belt Tensioner Brace is an inexpensive upgrade to eliminate this common problem. It simply bolts on to your stock tensioner and prevents any deflection of the cast arm. Already included with Edelbrock Supercharger Systems 1580, 1581, 1582, 1583, 1585 and 1587.