These universal paper replacement bags can be used with the Windsor® Sensor® S12 and Versamatic upright vacuums. Windosr® is a Karcher company, and they state that you must use OEM (Original Equipment Manufacturer) parts to honor your warranty. We typically tend to recommend these vacuums bags to people who are past their warranty period & are trying to save a few bucks. Same quality as OEM, just more affordable!