I'm not sure if I've understood you properly so if this is no help sorry in advance.
York sell 18'' dumb bell handles in the UK. Standard would be 14''. You can buy them individually and they cost about £7.99. They come as spinlock or with smooth ends that require some kind of clip. I've just bought a couple because I could not load my 14''s up beyond 30kg unless I used 10kg plates and that made everything too cumbersome. They haven't been delivered yet.
I had a quick look at York's US site but it's not very well structured so I couldn't be bothered to spend too much time on the job.