I have replaced ~3 Mac power adapters for free at Apple stores by taking a computer which has valid warranty coverage in, giving them the serial number and a fa

I have replaced ~3 Mac power adapters for free at Apple stores by taking a computer which has valid warranty coverage in, giving them the serial number and a failed adapter, and saying "purchased at the same time" (when it was an 85W which failed, and an MBA13 which comes with the 45W was my only laptop under applecare, or more recently, t-shaped vs. l-shaped vs. magsafe2 isses with my rMBP15. They never really complain; I honestly don't keep track of which adapters go with which laptops in general, but they're all obviously made by Apple, and failed due to manufacturer defect (yellowing and cracking of the plastic on the DC feed), so it's in Apple's interest replacing them for ~$25 cost, rather than annoying a $mm lifetime value customer.