A lot of jewelry makers do not like the crimped-bead look when it comes to finishing their jewerly pieces. Now with the crimp cover .. it ends up looking just like a lovely, tiny bead .. instead of a crimped look.
You will normally need a crimp cover that is just a little larger than your crimp bead or tube.
The industry norm on stating measurements is by the closed diameter. So if you see a crimp cover that has a size stated as 3mm, that usually means that it is 3mm in diameter when closed.
See detailed steps on how to use crimp covers ...