50 Horizontal Mounts, Black, Split-back, Pre-cut, 45 x 30 millimeters (1-3/4 x 1-3/16 inches) - Catalog # MM501 Archival-quality stamp mounts. Mystic mounts are easy to use. Mounts protect your stamps. Mounts make your collection more attractive. Stamps in mounts look great on an album page.