What do you call these?

Alan (California Radiant) Forbes

.........and where do you get them? Thermostat wire sleeve?

Edit: I just noticed the part number in the picture and found them on Amazon. It's called a "Black Universal Bushing".

Big Ed_4

Hozewatser

STEVEusaPA

Your hands are too clean…

mattmia2

grommet. maybe a bushing

JUGHNE

I end up with a can full of those type of things; snap in grommets or cord type locking grommets.
There are always some that come with FAF's.
Even plastic KO closers that make an electrical inspector blink and think....."now is that UL approved?"

It was good enough for factory equipment wasn't it??

I have taken the plastic KO snap in closers and drilled a hole with a step bit to run low voltage thru.

HomerJSmith

You gotta be kidding me. It's a insulation bushing for a single wire such as a thermostat wire. It fits into a 1/2" panel knock out.

You should be able to get them at any electric supply house. I save them, when ever I can, handy.

hot_rod

Wire grommets, find them at box and hardware stores. I like the rubber ones best, a lip on both sides to keep them secure

ratio

½" KO booshing, available in many sizes. I prefer the ones without the fingers inside, I can get wires through them easier. Bridgeport cat # 9792 for the ¾" size.