A few months ago I noticed the wipers were being sold with a $15 rebate offer.  I didn't need to replace them at that time but knew the day would come.  So I purchased a 20" blade and a 22" blade and put them into stock with my supply of filters, oil etc.  To my great pleasure, the blades I installed on 2/15/08 lasted 13 months and 14 days and were still perfectly fine.  They still wiped the window without streaking and without leaving wet spots.  So why replace them?

One of the blades lost the cover piece that goes over the center of the blade where it connects to the wiper arm.  And the black plastic was starting to dull a little bit.  I figured that I might as well replace the blades before they start to fail and put them aside as emergency spares.  Now I just need to watch for the next sale on these great blades!