This filter fits in the Miele New Complete C3 Cat & Dog Upright Vacuum my sister bought to clean up after two very fluffy Persian cats. Miele recommends changing the filter once a year or after around 50 hours of operation. My sister used the original filter for 2 years, by that time it had turned black (a normal part of the job) due to the material of the carbon brushes in the motor, although the timestrip indicator on the side of the filter was still green. An internet search revealed that to