I may be a bit thick but has anyone used this Thornes queen cage?

https://secure.thorne.co.uk/cgi-bin/..._ID=313634220#

The blerb states this:-

"A multi-use cage for posting, introduction, marking, trapping and gathering sample bees. The ergonomic shape makes it particularly easy to use".

However I am not sure how you could mark a queen with such a cage and although it has two compartments which are under a clip-in flap - presumably these two are for for candy - only one of the compartments has an entrance/exit to the outside world and this is through a zig-zag of plastic which may mean that bees can get in but the queen could not get out.