<html><head></head><body><div class="yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" data-setdir="false">I used Xcel Marine Foam, 1/2 inch thick. It's a closed cell foam that won't absorb water. It's available on Amazon. One roll will do two cars. Here is the link to buy on Amazon: <a href="https://www.amazon.com/XCEL-Marine-Closed-Neoprene-Adhesive/dp/B07G3J6294/ref=sr_1_1?keywords=XCEL+Extra+Large+Marine+Roll%2C+Closed+Cell+Neoprene+Rubber+with+Adhesive%2C+Size+60%22+x+16%22+x+1%2F2%22&qid=1636659970&s=sporting-goods&sr=1-1" rel="nofollow" target="_blank">https://www.amazon.com/XCEL-Marine-Closed-Neoprene-Adhesive/dp/B07G3J6294/ref=sr_1_1?keywords=XCEL+Extra+Large+Marine+Roll%2C+Closed+Cell+Neoprene+Rubber+with+Adhesive%2C+Size+60%22+x+16%22+x+1%2F2%22&qid=1636659970&s=sporting-goods&sr=1-1</a></div></div></body></html>