A small 50ml pill container.
This cache is part of the Blockbuster A to Z series.
An old 80's gameshow in which contestants had to pick letters and answer questions relating to that letter to get across the board and win.
If we were doing a modern day geocache version of this I would imagine it would go:
W.E.K.A: "I'll have a Z please Natalie247."
Natalie247: "This is a puzzling one indeed: At S46 12.ZZZ E169 38.YYY,
where ZZZ = (247 x 4) - 92
and YYY = ZZZ - 32 ?"
W.E.K.A: "So Z can be found at....."
Natalie247: "Correct - you won't need to store that away for later to see where i go with it."