I needed a 9 volt battery holder that included a belt loop to go with the wearable arc reactor created by MishaT (http://www.thingiverse.com/thing:32274) - so this is the work in progress version.Top cap is oriented incorrectly, and the fins are too thin/weak.Battery is held in simply by friction for the time being, does a pretty good job. The slot on the side is to allow for wiring to enter and to allow for fluctuation in battery sizes from different manufacturers. (and as a method to get the battery out...if said friction fit is too tight.