Adjustable earplugs. The Knops Original is a volume button for your ears. Knops is the first ever analog hearing solution, which is adjustable in multiple settings, and uses high-quality technology. But for all the technology in this product, there are no electronics. Knops neither require batteries nor an app. Indeed, you can use them always and everywhere. The Knops earplugs consist of four settings that help you reduce sound. Step 1 is the only setting that does not filter any sound and lets you hear everything loud and clear. Although this step doesn’t use a filter, it’s acoustically tuned. Step 2, 3, and 4 filter respectively 10dB, 20dB and 30dB (indicative). You can easily switch between the different settings by turning the ring. When to use Knops: At concerts, festivals, and clubs (to protect your ears); At the office, co-work spaces and cafés (to not get distracted and get your work done); During construction work or working with heavy (loud) machines (to protect your ears); During travel (to enjoy reading, do some work or get some sleep); While studying and making an exam (to not get distracted and work in silence); Color: Black