In reply to galpinos:
I just wanted to resurrect this thread and post about the excellent customer service I've just experienced from Power 'n Play (the CU belay glasses supplier in Germany).
I emailed them the other day, having lost one of the rubber sleeves that goes on the metal arm of their belay glasses, to ask about buying a replacement. This morning I received a full pack of replacement parts, including the sleeve I'd originally enquired about, free of charge. It was an excellent, speedy and friendly service from the team at P'nP, so a big shout out to them with my thanks.