This is a product imported from overseas. It's a gold metal sticker of the MARTIN logo. Although it's an aftermarket product, it's made with extreme detail and care. See the image for the size. The thickness is reportedly 0.3mm. Carefully peel off the blue backing paper, then apply the sticker with the transparent protective sheet still on. Finally, use something like the tip of a plastic pen to firmly press and secure it. Perfect for repairs, creating your own original guitar, etc.