I've replaced some switches inside of a box before, but never replaced the full box, so I am bit stumped on how to actually feed the wires into this Carlon B117RSW Old Work Shallow Outlet Box.
Since I've moved into my house, there have been a few outlets that were off, crooked, etc. I found one was out and when I went to adjust it, I found they had used a traditional retrofit box, but it was making contact with foam surrounding a waste water pipe (ugh). I bought this shallow retrofit box so that it wouldn't rub up against the pipe and I could get it flush to the wall. I figured the sidecar would provide a bit more space just to work with even if not needed at the end.
After searching the web and manufacturer's website, I really only found brochures - no schematic/instructions, etc. I'm stuck. Here is a photo:
In order to get the romex into this new box, what do I do? I don't see what bends and it's not clear if there is something I should punch out. I will be using the same outlet and wiring config (only one bundle comes into this box), so this is really the only hard part. I feel like there must be some obvious thing to do, but nothing seems flexible to bend or clear to break. Do I just break through the center of the V?
Edit:
Maybe this one just had more residual plastic between the slots then most? Screwdriver wasn't enough, really had to cut away the material between, but still flexes closed at the end: