Park Tool DT-2 Disc Brake Rotor Truing Fork Tool Disk

As with many Park Tools, you could probably get by with something else, like a crescent wrench.  We always used to.  But sometimes that can get you in trouble, like when the bend is farther down on the rotor arms an not just the brake track.  The DT-2 gives you two slots to true both cases.  It is thick, beautifully laser cut steel with Park's trademark blue vinyl handle coating that works so well.