b'A Door Sill That Never Needs Adjustment.Best Window & Door Product2016 Best of IBS AwardsTight margin: Loose margin:Sill cap compresses for smooth operation. Sill cap rises to prevent leaks and drafts.Z-ACs sill performance doesnt stop at the cap.Works with no corner pad: Works with wide margins:Z-End Base provides protection against Z-End Base seals even with water infiltration. wide margins.'