It's the one at the top of the page, hands-free glass and stand. This cost £20 with free p&p and is really great for taking a close look at your ants. I used it to watch my F.cinerea and C.cruentatus and I was amazed at how good the magnification is (2x) The ants really stand out and you get a better look at their details. It's especially good for checking how many eggs/larvae/pupa you have and seeing how well developed they are. I discovered that I actually now have 3 pupa in my C.cruentatus colony and not 2 larvae as I once thought with this. The hands free is a good addition too and it comes with a very good quality weighted base allowing the glass to be moved around more confidently with the flexible neck(The glass can also be unscrewed from the neck if you wish) I was able to position it quite low without it tipping over and got the perfect angle. Watching the F.ciinerea through this was great because of how active they are, and they look amazing up close.
I wanted something like this when I first considered keeping ants and this was exactly what I was thinking of. Highly recommended!
note: not sure if I've put this thread in the right place, feel free to move it.