Sorry, I worded that poorly. When you set your timing, you're pointing the tool towards the balancer and the light strobes when #1 cylinder fires. in front and just beside the balancer is the timing tab that has marks for every degree of timing from -10 to 0 to +10. With a traditional timing light, when the light flashes, you'll see that the timing mark on the balancer is aligned with a degree mark on the timing tab indicating where your timing is set to. With the timing light that has adjustment, the tool can strobe the light earlier or later by XX degrees you dial in on the tool. This allows you to watch for the strobe to light up the 0 degrees on the engine mark and your engine is actually set to the degree of timing indicated on the tool. Since the tool allows for more than 10 degrees, you've got more to work with.