JZ/BZ candy caps are used for feeding queens. They are durable, easy to use, and fit perfectly on the cages.
This candy tube has an hour glass shape to hold the candy in place. The candy cap keeps the queen from emerging. Along with the candy cap, you get a hanging strip which will hold your cage in place between frames!
How to use these caps: http://www.susquehannabeekeepers.com/pdfs/LJ_JZsBZs2017.pdf