An Optional velcro strap in black or gray was supplied – these straps connected to the primary male backlink of your bracelet. Thankfully, the fabric strap from the IW3715-36 and also the alternate rubber strap in the IW3548 in good shape the Aquatimer! Rolex makes about 1M watches a calendar https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/