roll bar question

i was looking into getting a roll bar setup for my car. on thunderracing.com they offer wolf roll bars. there is an option for jig notched. what is that?

The end of the tubes are already notched. You have to notch the tubes anyway so you can mate them to the other bar. Save time and money if you go ahead an get them notched. Plus they pre-scribe the bars for location. I orderd mine with them notched.

thanks