Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Bad specification

This battery is rated as a 5200mAh one but on arrival it was only a 4104mAh, which is 78% of the supposed rating and even less than the original Apple battery specification. There is no excuse for shipping a product with a bad specification like this, whatever the reason. It likely means this may have been old stock and had deteriorated with age buy that is not acceptable for a supposed new replacement product even if it was not going to last long term.