Double Belt Waist Trainer.

shows a sports armband phone case. These cases are designed to hold a smartphone securely on the arm during physical activities like running or working out. 

• The case is typically made from lightweight, sweat-absorbent, and water-resistant materials. 
• It features a clear, touch-sensitive window that allows you to use the phone's screen without removing it from the case. 
• The adjustable strap ensures a comfortable and secure fit on most arm sizes. 
• Some models also include a small pocket or slot for keys or other small items.