We ended up getting a hand on a pair of belay glasses while in the Red also. Having looked at, and considered, them for years, it became quickly apparent pretty much all climbing in the Red River Gorge is overhanging so our necks were taking a pounding leaning back to keep an eye on the climber.
In short: Your neck is very very happy from these. No more tight neck and shoulder muscles from belaying!
In length: While attending the Rocktoberfest, we met the USA-based crew who manufacture Belay Specs (official website). In short, they work exactly the same as other models on sale, only at the much improved price (in the USA at least) of $80/€60. Can't go wrong at that.
In short, they've been great. The case is perfectly sized to keep the glasses snug and stop them rattling around. They come with a cleaning cloth for keeping the glass nice and clear. The fit is fine for me, an after learning to make they sure they were fully pushed back onto the bridge of my nose to give the steepest viewing angle, they were perfect.
A couple of points to note (which affect all belay glasses):
- For some (including me), the first time I wore them I had a headache and eye strain, I think from focusing through the glass. After wearing them for the first two routes, I've never had it again.
- You don't look perfectly up, it's most like a couple of degrees forward from vertical. It does mean you don't stand directly under the person, but back a bit.
- As mentioned on the safety label inside the box, you shouldn't wear them for the first 6-8 metres as it's impossible to judge what is going on.
- When a person falls off, it can be tricky to track where they're falling. On our last day, on very damp rock, Naomi fell off while clipping a quickdraw (i.e. with the rope in her hand) about 6 bolts up a route - I essentially lost sight of her momentarily as I adjusted my viewing direction as she took flight. Most importantly however, you get used to it! I also suspect for this reason belay glasses might be dodgy on mountain terrain and rockfall (I suspect it would not be easy to dodge rockfall looking through prisms!).
Unfortunately Belay Specs can't be purchased in Europe at this time due to some interesting issues between them and CU glasses but if you're visiting the States, it's well worth keeping an eye out for them.