Nah not the roller, the attachment an anchor locks into at the end of a how sprit, they are usually glued to the bow. Its so you can winch in over roller of sorts but locks the anchor into place when under way.
Seems every manufacturer of them has a different concept.
Essentially you need a bow sprit (with rollers) to keep the anchor clear of the pontoons, when the anchor comes up it locks into place on the attachment, which doesnt seem to have a name as such.
One of the easiest solutions is the minkota deckhand on a sprit, but the anchor used is not the sort I would use in my water.
Anchor holder :-) according to this guy who admittedly said he doesnt know what its called :-)
Stronger make a whole host of solutions but very industrial looking. I wanted something neat and clean. I might contact a few big RIB makers to see what they use.
Mounting on an inflatable boat : Stronger