This arrow container appears to be a typical device to hold about a score of shafts. It has an aura of Alteration, however, if magic is detected for, and examination shows that it has three distinct portions. 

The first and smallest one can contain up to 60 objects of the same general size and shape as the sort of arrows employed with a longbow. 

The second, slightly longer compartment will hold up to 18 objects of the same general size and shape as a javelin.

The third and longest portion of the case will contain as many as 6 objects of the same general size and shape as a bow—spears or staves, for example. 

The possessor of this item need merely command the quiver to produce whatever item he or she wishes each round, ie. "an arrow +1", "an arrow +3", "a javelin"; etc.