I've been walking a rescue dog for the last couple of months since the passing of my wife, for a local kennels. I do it for exercise, and to keep her father/my father-in-law company. Eric is a Great Dane - very big but fortunately very placid, and this is one of a set of caches that follow one of the main walks we do around Treeton Dyke.
Placed in a location that at the time of doing so was full of magpies, birds which my late wife had a great affection for. You are looking for a black tube (a pop-bottle 'blank').