I can’t answer the part about how you’d put two of them together … perhaps a piece of appropriate-diameter brass tubing inside at the join? … but I have this type of connector and it’s great. Crazy-flexible and thus MUCH more accommodating to my middle than the black or clear tubing. Thinking of ordering another for my new set, but haven’t gotten around to it yet. Thanks for the reminder!
The connector is 6" long. One of my sets has a fairly long blowpipe, and the 6 inch connector is the perfect length. The other set has a short blowpipe so I have part of a second connector fastened to it and I use a piece of 1/2" ID vinyl tubing to connect the two. The tubing is a bit slick so I’ve run a pin through the connection between the short connector and the tubing to make it permanent. The other end occasionally slips out, but that only gives me another opportunity to curse at my pipes.
A good wash with dish soap helps. In early days I had a little fabric sleeve over mine to protect my clothes (also because it was so industrial-looking), but that was lost along the way. I think I remember wrapping it with a layer of Vetrap (Coflex) at one point, too, but I don’t even notice the tube now.
If you have silver or silver plated pipes it’s worth noting that the black rubber connector’s will tarnish the silver where it comes into contact. More of a problem if your set is silver plated as with prolonged contact it eats into the plating.
NPU changed the rubber hose a few years back from matt manure sulphur flavour to a shiny plasticy rubber with no nasty smell.
I bought the stinky one years ago at wcss and had it in my coat pocket all week, I thought it was just the country air I was sniffing but it was my pocket.