Hoover replacement filter is for the Hoover air aurifiers series WH10100 and WH10200. Replacement appears to be exactly like the original. It is good idea to replace filters periodically.
Hoover Replacement Filter
Some reviewers accurately pointed out that it does generate some noise, which can be an issue when trying to sleep.
Hoover replacement filter can be used for Hoover air purifier with TIO2 technology WH10600.