Compatibility: Compatible with Shark Detect Pro Cordless Stick Handheld 2-in-1 Lightweight Vacuum Models IW3511, IW3120, IW1111, IW1120 Package Contents: You will receive 1 pack back HEPA filter and 2 pack prefilters Easy to Install: Effectively prevent dander, dust, hair. Improve the surrounding air quality and protect your health. We recommend replacing filter every 3-6 months to extend the lifespan of your vacuum cleaner High Quality Material: Our HEPA filters are of high quality and more durable. Made of high-strength and environmental protection material Please do not hesitate to contact us if you require any information or face any issues. Our dedicated team is on standby, ready to offer the informational support you need. Your satisfaction is the ultimate measure of our service Compatible with Shark IW3511 Detect Pro Auto-Empty System, Also Compatible with Shark IW1111 Detect Pro Cordless Stick Vacuum, 1 Pack Back HEPA Filter and 2 Pack PreFilters