The Triangle storage box is a hard shell EVA case for storing accessories. It features a foam separator to stop tools from rattling against each other which can also be removed should you want it to store a tube. It also includes a side pocket for extra storage.
This unit includes two mounting straps and a mini rail, this used for mounting the triangle box to other areas on your frame. See the second image in the gallery for an example.
Check out our Holy Rail archive, we are documenting successful Holy Rail setups for reference purposes: