Shower hose attachment fitting?

I have got to replace a shower hose as its split. The problem I'm having is that the attachment that goes into the shower unit is different from the one that attaches to the shower head (basically it is smaller). When I look in the DIY shopes the hoses have the same attachments at each end and they are slightly longer. The same as the size of the attachment that screws onto the shower head. I need one with a smaller attchment the other end

Poldark
January 2011