Your muscles become more powerful each time you train, and now you can amp up your breathing game with the Training Mask 2.0 Black Out Respiratory Training Device. Put on the mask, secure the neoprene strap and start inhaling fuller, deeper breaths and using oxygen more efficiently as you push your body. Enhance your endurance by adjusting your level of breathing resistance up to 15x as your lungs and diaphragm get stronger.