Mophie’s battery cases offer protection and extended battery life. This particular model will work with both the iPhone 5 and the iPhone 5S. The normal price is $99 — $68 on Amazon — which means that this deal is fantastic.
The only reservation I have is that the products are “recertified”; hopefully the batteries have been replaced, but it isn’t guaranteed that your battery will be free from any usage which could negatively impact performance. Still, for $35, it’s hard to say no to this if you’ve been looking for a case that could extend the battery. Act quickly, as the deal won’t last forever.