Genuine Kirby Cloth Vacuum bags. 

These bags are universal fit style, and are the top of the line Cloth filtration bags, great for filtering out allergens and dust from your homes air. 

These bags fit Kirby models G4, G5, GSix, Ultimate G, Ultimate G Diamond, Sentria, Sentria II, and Avalir models. They fit both F-style and Twist-style adapters, as well as newer style Kirby's taking the Style F vacuum bags.