Electrolux SC535 BackPack Vac QuietClean HEPA Filter 10 Qt Cap Black Sold as 1 EA. CRI Seal of Approval - Committed to delivering an exceptional cleaning experience backed by certification from the Carpet and Rug Institute (CRI). HEPA Filter - Sealed HEPA system captures particles for improved air quality. Do Not Disturb 24/7 - Our premium line of QuietClean machines provide 24/7 any time of the day cleaning at 70 dBA or less which is equivalent to the noise level of a human conversation. LEED Daytime Quiet - Clean quietly and efficiently during the day with our 70 dBA or less machines to help businesses keep energy costs down and maintain their LEED certifications.