UpStart Battery Replacement Lasko 1115 Humidifier Filter - Compatible Lasko THF15 Air Filter Replacement Lasko 1115 Humidifier Filter Replaces Lasko THF15 Air Filter Traps Water Impurities & Dissolved Solids Before They Become Airborne For best results, change air filter at least once per season or more often depending on air quality and use. Essential for Allergy Sufferers. On Sale for a Limited Time!