Genuine Dyson DC19T2 washable pre filter

When would this part need replacing?
When it is damaged
When it looks worn or the sponge will not regain its shape.
When you need a spare

Fits The following DC19 models:

DC19, DC19 Comet Exclusive, DC19 Allergy, DC19I, DC19 Plus tools, DC19 Precision, DC19 Tool kit, DC19dB, DC19dBi, DC19dB Mail order

Genuine Dyson DC19 washable pre filter 917189-01