Excerpt: You're here for the same reason I am - our frail, overpriced ac adapters either broke, frayed or no longer charge. Probably after less than a few years.
Apple computers are great. Their chargers are junk. They know it - check out the reviews on Apple's own site - and we know it.
Summary: In keeping with Apple excellence this product is much improved over their earlier style of plug. Each of the plugs had magnetic connections. The new one however is made offset. This design saves the plug from the chord pulling off of the main wire.