Bought this for an aftermarket car audio installation project that never materialized.
Material is a high-density polyethylene (HDPE) and will not rot unlike wood.

Thickness is 10mm / 1 cm. Comes as a pair. 8" speaker opening. Please see measurements to confirm it works with your application.

Originally bought these for my 2004 WRX and according to the site, this will work with year 2002-2007 Imprezas. Formerly SubaruAudio.net and later rebranded to http://carstereoadapters.com/ 

Ships from Canada. Canada Post for Canadians buyers. USPS/Fedex for USA buyers. I only ship once a week due to work. So please allow time for a tracking. Thank you for understanding.