I got one of these hob overflows used, but pretty much new for cheap. It seems the previous owner was tinkering with the standpipes. First, they are about 3mm from making a tight sealed fit, it's very strange. They have another piece of smaller acrylic tube glued inside the standpipe as some sort of vent, and it came with some maggie mufflers. I am going to make some proper fitting standpipes so they seal in the bulkhead fitting, but I am unsure how tall they are out of the box. All the photos I found online show them with a filter tube over the standpipe so I can't guess the height.