In reply to UKC Gear:
I've been using one of these for the past month or so. Despite all the talk online as to how you can make something similar by taping a toothbrush to a stick (which you can), or by using a sawn off bog-brush from B&Q (which you also can), all the people I've met at the crag have had nothing but positive things to say about it - as such I'd anticipate they'll be quite popular in years to come.
That said, I completely reserve the right for people to make their own or use a cheaper alternative. This is just a good option for those that don't want to (of which I suspect there are many)!
p.s. I'm with you regarding the selfie thing, but as I'm over 30 years old suspect this particular element of functionality wasn't designed with me in mind
Post edited at 16:04