If no comment is provided, we will ship the M size. ■ This is a band that can secure the shoulder straps of a backpack. ■ Easy to attach and detach with a buckle, hassle-free! ■ Adjustable length for a perfect fit. [Product Contents]: Chest Belt [Product Size]: S size (for children) 　Belt: Approximately 2cm wide, approximately 34cm long (maximum) 　Buckle: Approximately 2.3cm x 4.6cm M size (for adults) 　Belt: Approximately 2.5cm wide, approximately 37cm long (maximum) 　Buckle: Approximately 3.0cm x 6.7cm [Material]: Nylon ○Notes on Use○ ※Instruction manual is not included. ※Specifications are subject to change without notice for improvement. ※The color of the product may differ slightly from the actual product due to the environment of the display screen. ※Imported products may have minor stains/damage. ○Please agree to the above before purchasing!○