Simplex quick release with rubber cover.
 

I remember seeing some of these on ebay a while back going for a lot of money. They seem to be pretty rare, but are they worth much? I just have a front one with a mostly intact white cover.
Thanks, I'll try to get some photos up soon.

Yes, some of them are worth something to some people; not sure why. I think the white are earlier than the black. I have a pair of black ones here someplace.

The deep-pockets Japanese collectors of vintage French parts can bid them up when they are in nice shape.

a good set complete with intact black wingnuts and rubber can easily go for $200 on ebay. Is your skewer complete? I could be worth say $50-75... all depends... I sold a set for $100 with nut rubber but the rest was there for over $100... a couple years ago.

It's the plastic wingnuts that are hard to find. I had to buy a rusty pair of skewers just to get the wingnut I needed. The wingnut is missing from most of the Simplex skewers I see. The thing is, the wingnut is not necessary. It acts as a locknut for the metal nut and skewers don't need a locknut. It just doesn't look right without the wingnut. Little details like that are important to me and it costs me.

I can't believe someone is actually paying money for those godawful things. From what I remember, mechanically they were awful. Give me a cheap Japanese skewer any day.

The last time I saw a Simplex QR with a plastic wingnut was on my 1967 Peugeot UO8, which I sold sometime in the 1970s. When I first bought the bike, I had no idea how the QR worked and tried to tighten it using the plastic wingnut, which pulled the embedded hex nut out of it. I subsequently bought a Gitane Interclub, but it came with a normal Atom QR. Ditto a recently purchased 1970s Mercier.

That's the difference between a historically accurate restoration using pioneering, ground breaking components... or a functioning working piece of equipment to get you down the road.

The same could be said about a 1962 Ferrari 250 GT and a 1992 Toyota Supra... which one has better reliability and which is faster? Toyota hands down... but which would you rather have?

It all depends on what your interests are and what your goals are for the bicycle.

I think they work very well.

I agree... and I need one of those plastic wingnuts too!