The D-Cache Fuse Pack is designed to work with the Fuse end cap which gives you the ability to exchange plastic "fuses" of different colors to identify the contents when using multiple D-Cache units. The integrated o-ring in the cap retains the fuse and provides easy pull-out/push-in replacement for a fuse of a different color. Each fuse is approximately 1-1/2" long. What you get: (10) Plastic "fuses" of various colors