I've bought these twice and I'm buying more.  Whoever designed the strap attachment is a genius!  I'll try to describe it (this is the left side).
Imagine that you used wire to form the outline of a long narrow heart shape.  Now imagine that you laid that heart shape on its side, with the rounded part of the heart at the left.  The side of the heart that's now the upper side is slanted and the strap is attached to that.  Results:  a strap that never inches its way off my shoulders and never falls down!  The other good thing is that the ones I just ordered in October are tagless and I'm finding that I want to wear those instead of the older ones with tags.  The cotton lining is what first made me buy these but the newer ones are even better.