I'm not sure about the Duotone/Core adapter, but the cheap SUP pump from BCF fishing shop fitted my Naish wing if they are the same.

Hey, you can purchase the regular 'cheapie' sup pump adapter with holes in each side and then cut a round disk out of a piece of foam mat (or something like a jandal) and then cut the center out so it fits exactly over the valve adapter - that's what I did, it worked and it cost me nothing. If I've got time I'll nip out and grab a pic of what I mean







Oh yes, I forgot, I think if my memory is still working that you have to sand the 'cheapie' pump adapter OD down about 1-1.2mm with a file or some sandpaper otherwise it's too stiff to insert and too stiff to turn - I got there with a non duotone adapter after a bit of farting around, lol