Replacement Mylar windows are sold in packages of 2 sheets of 20 windows each (mylar windows are included with holders). These windows have an anti-static coating to eliminate the attraction of lint from static electricity.
Available in two gauges:
THIN (4 mil) for use with half dollar, Morgan dollar, and $20.00 gold size holders. These replace the former 3 and 5 mil gauges.
THICK (7 mil) for use with cent, nickel, dime, quarter, and presidential and Susan B Anthony dollar size holders.