Selvedge Rollers

Called "Tension Rollers" in the manual, these fit onto the long rod that goes across just under the front beam. They look like this in use:

The device holds the roller itself - like a super-prickly little pine cone - against the underside of the cloth. The teeth on each roller are aimed toward the edge of the cloth, so that it always wants to pull the cloth out to its full width. This prevents draw-in, which can cause edge threads to break from high friction as they pass through the reed in a non-straight line.

These are an alternative to using a temple. You can see a temple in use in this picture, across the cloth that's just been woven:

It's a bar with sharp teeth at each end, you set it to the width you need and it keeps the cloth that wide. But it must be moved up the cloth regularly as you weave.

This is where selvedge rollers have a distinct advantage. They do not need to be moved, they just stay in place as the cloth moves past. Very convenient. They are covered in very sharp little needles, though. I scraped my finger pretty good on one when reaching into a box where it was located, early on in the loom set-up. I have had zero incidents so far while weaving with them, though. And they do seem to work.