Soundown Vinyl Foam Composite Insulation 1.5" x 54" Per Foot Optimist swelling or shrinking is effectively swelling or shrinking is effectively absorbed Both pennant mounts can move either direction on the flagpole allowing flexibility in mounting various sizes of flags where the eyelet's of the flag are less than the over all length of the flagpole The composite is designed and manufactured specifically for attenuation of sounds from machines such as engines In areas where hatch and bulkhead clearances do not allow the use of thicker composites you may substitute heavier barrier material so that performance is not compromised