Both Red Trumpet and Music Direct are selling 3-ply polyethylene sleeves that match what I believe Cpdunn99 is describing. Here are the links to their descriptions:
Music Direct
http://www.redtrumpet.com/accessories/item.php?item=22667&sid=1205748496
Music Direct
http://www.amusicdirect.com/products/detail.asp?sku=AMFIS
Music Direct
http://www.redtrumpet.com/accessories/item.php?item=22667&sid=1205748496
Music Direct
http://www.amusicdirect.com/products/detail.asp?sku=AMFIS