Supertop fabric is produced using Haartz 18oz vinyl denim that's mildew and stain resistant., The thread is marine grade T-135 industrial strength, Bestop uses high quality scoop-counted, nylon coil zippers for ease of removal and replacement, and sealed seams for water-tight protection.New Supertop? has "Cool and Convenient Features". Bestop's Supertop let's you zip-out the rear window and roll-up the side windows for serious open-air driving!You can now unzip the side window for easy access to the rear cargo area of your Land Cruiser. No more snaps to snap or climbing over your front seats to get something from the back. Just unzip the side window and grab a coat or a drink.