Rolleiflex meter diffuser questions

Awhile back I bought this diffuser for my 3.5F. My understanding is that they're fragile, so one should leave it on and always do incident metering rather than popping it on and off and switching between metering syles. Are they that fragile?

Anyway, I've yet to use it and may never use it. What is the value of these things? I see all sorts of prices on ebay and I see there are Chinese copies which look identical to the original - at least to me. Is this one an original or a copy?

Yours looks like a original part - I have a (Chinese made) copy for about 25 US Dollar.
I use it rarely with my 3.5F (though it is reliable for incident metering) - I prefer my handheld Gossen meter.
Those older ones might be fragile - my copy seems sturdy.

I have one fitted to my 1960 Rolleilflex 2.8 F Planar bought years ago from a Camera Club member for £250. The METER still works accurately and I used it for the 'Incident Light'method every tine for Weddings and it was accurate!

Rollei 2.8F Planar by Peter Elgar, on Flickr