Check the listing for details. 8" Subwoofer Speaker Spacers Depth Extender Extending Rings - 1/4" thick SSK8. Condition: New. Listed at 17.79 USD. 8" Subwoofer Speaker Spacers Depth Extender Extending Rings - 1/4" thick - ID: 7 1/8" OD: 8 7/8" - 1 Pair . SSK8 - Stackable - Perfect For Framing Fiberglass Enclosures.8" Subwoofer Speaker Spacers Depth Extender Extending Rings - 1/4" thick - ID: 7 1/8" OD: 8 7/8" - 1 Pair - SSK8 - Stackable - Perfect For Framing Fiberglass Enclosures. Our speaker spacers are made to the highest quality standards, right here in the USA. They are made from CNC machined PVC plastic, and will not rot like MDF (medium density fiberboard) or wood. Our speaker adapters are tough as nails. Whether replacing worn speakers or simply upgrading, our speaker adapters will allow you to install your aftermarket speakers with ease. If you do not see compatibility for the make/model of your car, messages us we can provide more models/makes of adapters.