Not so great speaker adapter
1996 Porsche 911
Crutchfield Customer Review (What's this?)
Flimsy. Not large enough to cover the area needed as an adapter for a 4x6 speaker area. Cutting from MDF solution worked better.
Pros: Provides the circle size for a 4" drop in.
Cons: Had to use MDF cutout instead. Not substantial/stiff.