PET Ultra Clear Binding Covers, 5mil - Letter, 100pk. Fellowes PET ultra-clear, heat-resistant binding covers highlight your title page. Durable plastic protects bound documents from spills and tears. 8-1/2" x 11" size with square corners. Un-punched covers easily adapt to any binding system. Not for use with Helios binding systems. 7mil thickness. 100% Recyclable.