A new Zipp disc rear wheel is supplied with a right-angled doo-da to allow you to get a pump attached onto the valve in the cut-out in the wheel...
Zipp right angle inflator by
Ron Lowe, on Flickr
This appears to be a 2-piece thing.
I'm quite unable to get it to seal in any useful way.
There's a short stem which screws onto a presta valve, with an end which looks like it should be crimped onto a hose!
But the end that screws onto the presta valve has no sealing elements at all, just a thread.
Then there's the right-angle thing which looks like a small weed pipe.
It has a rubber seal in the valve-facing end, and a schrader-sized thread at the pump end.
How in the name of hell are you meant to use this?
The short stem doesn't seal properly against either the valve or the right-angle extension.
The right-angle extension on it's own Just About seals against the valve on it's own, if you leave out the short stem, but only if you have four hands and gorilla grip strength to clamp it in place and operate the pump at the same time. There's no clamping lever or anything.
It all seems to be a PoS to me, but perhaps I'm doing something wrong.
I might buy something like this, which looks like it threads onto the valve allowing me to operate the pump with my remaining 2 hands:
https://www.topeak.com/global/storage/app/media/download/product-manual/Pressure-Rite%20Presta%20Valve%20Adapter/pressureriteprestagb0813.pdf