Shanxi's link sums it up well. I have one of these in my
gallery (not as nice as the subject of this post). This is what I wrote about it:
Since they were first struck at Hall in Swabia, these coins became known as "hellers" (or as handhellers, due to the devise on the
obverse). They were struck in large quantities but of a
poor quality, and circulated widely, quickly driving all other small coins out of circulation. The name "
heller" became associated with coins of the same
type struck in other cities, and by extension, to coins of low grade
billon throughout
Germany.
The
obverse devise also appears on the coat-of-arms of Hall, and it is not clear whether or not the coin preceded the coat-of-arms. The word "handel" means trade or commerce in
German, and the hand may be a pun.
Stkp