Why You need to use Speaker Adapters with aftermarket speakers | AnthonyJ350 - YouTube
Door Speaker Adapter Bracket , 6.5inch Wear Resistant Speaker Adapters Professional High Strength For Car 6X9,8X10 - Walmart.com
PVC Speaker Adapters - CNC Machined - In Stock or Custom Made
Leewa 2pcs 6x9 To 6.5" Car Speaker Spacer Solid For Subaru Forester Front Door Audio Pad Mat Adapter Modified Rings Kit #ca5523 - Cables, Adapters & Sockets - AliExpress
Metra 82-6900 1-1/2" Plastic Spacers and Depth Extenders for 6" x 9" Car Speakers - Pair
SMD Ford 3-Way Speaker Adapters - Sky High Car Audio (PAIR)