Third Eye Chain WatcherThe Third Eye Chain Watcher is probably the least expensive way to prevent your chain from accidentally dropping off of your chainrings onto your frame. Essentially once mounted, the small resin bulge sits close enough to the chain so that if the chain starts to overshift, it wont slam into the frame. Protect your frame from the potentially significant damage that might ensue from a metal chain smashing into your paint finish (or worse, digging into your carbon frame).730366010008