For determining maximum lung volume (vital capacity). Student exhales fully into a bag, then squeezes the expired gas into the bottom of the bag. Vital capacity is read directly from wall of the bag (marked in 100-mL increments up to 6 L). Set includes 4 heavy-gauge plastic reusable bags with mouthpiece holders and 30 disposable mouthpieces.
Order item# 692647: Mouthpiece Replacements.