Help to find a item of tackle

Can anyone out there help me put a name to a item of tackle for storing old fly fishing tippets , its plastic about 2 ins long and his rounded ends , it has a slot runing up one side , inside it has a rotating brush like device that can be turned from one of the rounded ends , on the other end this is a clip to attach to your vest . I must be losing my marbles I can no remember where I got it or with it is called .

A mono master...?

Thanks mate .