Made of super soft and non-toxic sponge, comfy and skin-friendly. Slow rebounded time in 30s-60s to help earplugs to be inserted into the ear canal for a better fit. With a Noise Reduction Rating (NRR) of 33 decibels, effectively protect hearing in loud events or set up quiet environment for sleep. these versatile, noise blocking earplugs are great for sleeping, studying, work, travel, concerts, relaxation, motorcycling, loud events, etc. the small box is also very convenient to carry around. QTY over 40000 ship by sea.