The Ocean Band is made from a high-performance elastomer shaped in a tubular structure. This allows you to stretch it for a perfect fit, even over a wetsuit. The titanium buckle and adjustable loop secure the band during high-speed water sports. To ensure you can wear the Ocean Band over your thickest wetsuit, a separately available extension is offered. The Trail Loop, Alpine Loop, and Ocean Band are designed for the Apple Watch Ultra and fit perfectly with the 49 mm case. The bands are also compatible with the 44 mm and 45 mm cases.