Have not been here for a while and don’t know if this has been discussed already.
Knit Pro from Knit Picks make connectors for their cables, Somebody on Ravelry have said they are not on Knit Picks website.
maybe knitters in the US should call them up and find out why.
I ordered mine online form a shop here in the UK about 3 weeks ago.
http://www.first4yarns.co.uk/cable-connectors-3156-p.asp
Anyway just thought I would let everybody know who is interested.
I would buy those if Knit Picks would get them.
Besides doubling a cable, which would seem like it would drag on the stitches, it would make changing to a different cable easy.
If Knit Picks have a freephone or email contact you could ask them why they don’t have them.
These are made by Knit Picks to go with their needles and the shop that sells them in the UK bought it direct from Knit Picks.
They aren’t something I’d use a lot, but they would come in handy for some projects. I just emailed them to ask about them. 
I’m wondering if I’d like the ‘bulge’ in the middle of an otherwise slick, smooth, thin cable. :?? Would this ‘hang up’ the knitting?
Options extra-long and extra-extra long cables are so inexpensive,
I purchased a set of each for ‘in case’. I have used them a few times each!
I have a set of 47" and 60" cables. I think KP should sell 47" and 60" for half the price, and include just one cable. As it is, a set is $3.99.
I have the connectors, and I LOVE them. I do a lot of fit-as-you-go knitting, so it makes it really easy to just add on more cable and try the thing on. They don’t seem to hang up the loops or anything. I order them from GetKnitted.com, in England.
I just now got a reply so as of now they don’t plan to offer it and indeed is not KP product.
At this time, I am not aware of any plans to offer a cable connector. The product you see in Europe is not actually Knit Picks product. It is made by the same manufacturer, but the brand is Knit Pro. They sell and distribute their items in Europe and elsewhere. However, I will pass along your request as a suggestion for future product.
That is interesting, when I first started to buy KP options needles and cables they were labeled knit picks now they are labeled Knit Pro formerly knit Picks. These connectors are also labeled Knit Pro. I have just looked at the packaging and they give a EU website so I imagine Knit Pick have set up a European company to supply us with needles and they maybe do their own thing.
That is why I was so excited to find them. Trying to get a circular lace shawl on five different circulars to take a photo is a bit of a nightmare and with these little beauties it will make it a lot easier to take progress photos of your work or trying on a sweater while you have it on the cable.
Knit Pick worked with a company that I think is in India (someone once told me that, but I never tried to find out if it was correct or not) to develop the product that they now sell. The company in India developed products for the line that Knit Pick didn’t want to sell for their own reasons, and Knit Pick apparently also didn’t want to go global, so Knit Pro is the company set up to handle distribution for everywhere BUT the US – I believe Knit Pick has nothing to do with Knit Pro at all, in terms of the business.
It’s worth keeping an eye on both. I ordered the cable connectors and the smallersized needles (3.0mm and 3.5mm) as soon as they came onto the getknitted website! I need to get a set of 15mm tips as well…maybe time for another order. 