I know about expansion and contraction and take good care of my little GS171 YAMAHA flamenco,(well kept humidity level room and away from sunlight too) I have been disappointed with these strings, They must have a very short shelf life compared to other brands. Over a period of three years using at least three three set boxes.. I experienced that every replacement set , one of the low silverplated strings will break /pop/snap on the guitar on it's own just sitting on the stand. I own many acoustics and electrics and playing for decades, no set a strings break this fast. I would not recommend these after having this problem for at least six sets of three packed strings over the past few years.