Made of food-grade silica gel, this training item allows for adjustable resistance. - Color: Black - Size: 10cm x 3cm - Material: Food-grade silica gel - Adjustment: Adjustable resistance - Features: Washable, economical, easy to use Breathing trainer to strengthen lung capacity, train respiratory muscles, practice diaphragmatic breathing, and improve lung function. Easy to install, made of food-grade silicone, for fitness. Thank you for viewing.