I purchased one of those Bull Boxes some years ago after seeing it demonstrated at Blackpool by the guy who made them,his name is Andy Heal and he ran a business called Homestead Joinery somewhere down the other side of Bath,up until this year he as allways had a stall at Blackpool selling pigeon stuff but he wasn,t there this time,there was a video issued with the box that showed you how to use it but unfortunatly I sent it to a pigeon basics member in Scotland to have a look at and i,ve never seen it since,the box as a large section in the middle where the cock goes and also two hen boxes on either side of that.I dont have the box any more though.