EnviroCare 18 Hoover Windtunnel Upright Type Y Vacuum Bags (Micro-filtration) 2 packages of 9 bags for a total of 18 total bags Envirocare bags are 30% more efficient then standard paper bags A Must Have For Allergy and Asthma suffers 99.7% of all dust particles are captured with Envirocare bags Compare With Hoover Part # 4010100Y