I have never used them and was wondering how effective they are for coons.Thank you.

There was a guy that used them last season or the season before. I cant remember his user name. You may want to post this on trapper talk too as that is where he was posting the pictures.

Your PM box.

I've been using 4 gal square buckets with a 10-12" roof, overhanging the opening, and have yet to catch any of MY COUSINS coon hounds that he runs on our creek.
He has seen his dogs sniff around the buckets, but not got down to belly crawl into a bucket.
COULD IT HAPPEN?..., sure....but some old pro's gave me the tip on using a roof and it seems to work for me.
My roofs detach with 2 wing nuts for quick assembly and allow buckets to stack and saving space.

MAKE SURE TO CHECK YOUR STATE LAWS....some states have a box opening restriction.

….and I cover the bucket with local debris, and drape a vine or grass over the top of the jaws, so it looks like a pocket in some brush.,,and often use pans instead of wire triggers...suspend the bait so mice can't get to it AND their attn is up, 1/4" rat wire back window about 4"x4", pop rivetted in place, for scent flow thru. I stake the whole works down with a t-stake thru the edge/side of bucket running the stake thru the loop on the end of traps chain underneath bucket.

...keep in mind though, I'm not a long liner and my time isn't as valuable as other folks time.
It takes about 5 mins to set up a bucket , BUT in the same 5 mins I can set up several DP's.

I would keep in mind that "dog proof" buckets and boxes is what got body grip traps banned on land in some areas/states. Maybe you will never kill a dog, but others have and it makes big bad news when it happens. I think coon dogs, at least mine were, are least apt to be caught in such a trap because in the field they are focused on 'coons. Lap dogs are the ones to be concerned with and maybe beagles.

Plenty of dogs running around that are smaller than the coons we trap. Bait selection can be critical. Keep the meat baits out of the boxes if any chance of a dog.

And what TJM said

They are very effective for coons, here where I use them.