![Round Calendar Windows (3.50 mm to 6.50 mm)](http://perrinwatchparts.com/cdn/shop/files/CR-CALWINLINEDRAWING_300x243.jpg?v=1684939190)
Magnifying Calendar Windows can be fitted on any flat watch crystal, mineral or sapphire. UV cement (Product # 12-207) is highly recommended for a clear and clean result. Magnifying calendar (date) windows are available in either round or rectangular shapes in a wide variety of dimensions.