Make no mistake, this is a very rare 13ZN! Few were made with sandwich dials and few have survived... These dials are considered to be the most beautiful and desirable as they most tipically were made in the second half of the 1930's (and are now widely copied in modern watches). They literally have something extra... below is a copper plate and the top dial has the numerals cut out to give a 3-D like appearance. This one is all original and is the rarer large variant with blue/black print (3 color dials are more common). It's hard to capture and photograph but it's in lovely aged condition (most are in worse condition or re-painted) and shows it's age gracefully. The beautiful  blue hands also match the inner snail scale. The case measures nearly 37mm and bears reference 3757. It was serviced at the Longines factory in 2017 and received a large Certificate of Origin and Authenticity, meaning that everything is still like it left the factory in 1937! It further comes with a rare Longines box and buckle. A true collectors dream.