Chamfered brake pads

[Mustangman]

The chamfer is designed to reduce brake squeal. Some pads will “ring” when at full thickness and reducing the contact length when at full thickness by adding a chamfer can help this. As it wears down the pad no longer “rings” and can take the full length. As other posters here have said, some pads come that way. Some pads have a slot cut in the middle to help this, too. Some mechanics will add their own because they think it will reduce bring-backs for noise.