The fences have recesses for tapes (a left and right are included). I picked up a couple more, this one reads from left to right with zero at the end of the fence. Just line the end of the stock to th end of the fence to get your measurement.

When you need to get a measurement from a point that you can't hook the tape onto, try this. Set the the tape and the point you need the measurement from on the end of the extension wing........

.....now pull your measurement. The sawhelper really is made for everyday transport to the job, it breaks down/sets up easily. Folds up to fit in the truck nicely too.

Here is a short video of the setup.

Check them out on the web, Sawhelper site.