[phatdaddy]

This trap is for stone crabs, not blue crabs. When they drop in the hole on top, they would have to crawl up the sides, across the top, over the lip, & out the hole. The 4" coupler is flush on top of the trap and recessed about 4" into the trap. You only have to check these about every 3 or 4 days. I had one I lost last year for about 3 months. When I found it there were 17 crabs inside. The bait had long gone, but I think they were using it for shelter.