K9 MASK AIR FILTER FOR DOGS WITH THREE (3) ‘EXTREME BREATHE’ AIR FILTER REFILLS- Protection for your dog from wildfire smoke, ash, dust, chemicals, pollen, smog, and ozone.- PM2.5 extreme air filter protection for filtering harmful micro air particles and pollutants.- Best in ‘Unhealthy’ to ‘Hazardous’ AQI 250-500.- Neck and muzzle adjustments for secure fit on various dog breeds.- Washable mask with replaceable air filters.- Reflective materials for low-light visibility to protect a dog’s safety in the dark.- Functions as a muzzle to protect the dog and others during anxious situations.What is the Right Size K9 Mask for My Dog?- Muzzle Circumference (most important measurement for sizing):- Measure around the dog’s snout near the eyes using a soft measuring tape. Or use a shoelace or phone charging cord around the snout and measure with a ruler or tape measure.- Important Note: If your dog's muzzle circumference is in between sizes we recommend you get the larger mask size for more panting space.SMALL:- Muzzle Circumference: 4.5-6.5 inches (11.5-16.5 cm)MEDIUM:- Muzzle Circumference: 7-9 inches (16.5-23 cm)LARGE:- Muzzle Circumference: 9-13 inches (23-33 cm)EXTRA LARGE:- Muzzle Circumference: 13-17.5 inches (33-45 cm)AIR FILTER USE: We recommend using each air filter up to four hours. The K9 Mask package contains (3) ‘Extreme Breathe” air filters.HOW TO INSERT FILTER INTO MASK: Align air filter inside mask so all edges of air filter fit against sides of mask. Expect tight fit in mask. INTRODUCTION AND TRAINING FOR YOUR DOG: Your dog may require a 1-3 week training period to effectively wear the K9 Mask. VISUALLY MONITOR YOUR DOG: We recommend you use the “Extreme Breathe” air filter for 10 minutes at time with a small break to verify your dog is not overheating. ANSWERS TO FAQ & VIDEO TIPS - K9Mask.com