AirClean 3D Efficiency Dustbags (Type U for the Dynamic U1 Series) Only new AirClean dustbags from Miele will feature the new AirClean Close dustbag collar. The color of the AirClean Close dustbag collar will be exclusive to Miele dustbags. Blue for G/N [used by Miele's Complete, Cat & Dog, and HomeCare Series], Green for U [used by Miele's Dynamic U1 uprights] and Red for FJM dustbags [used by Compact Series]. Improved Technology Miele’s revolutionary and patented dustbag is an important component of the vacuum cleaners filtration system. Our unique AirClean 3D EfficiencyTM bag is a 9-layer fortress of electrostatically charged material that traps micro-sized debris in the airtight vacuum chamber. With its spring-loaded, self-locking collar you’ are never exposed to the tiny, lung-damaging dust and allergens you worked to vacuum up!