An Optional velcro strap in black or gray was supplied – these straps hooked up to the main male connection from the bracelet. Fortunately, the fabric strap through the IW3715-36 along with the alternate rubber strap from the IW3548 fit the Aquatimer! Christie’s This was mainly a ref. 6538 — https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/