【Guaranteed Noise Reduction】 The noise reduction performance of this product complies with the US standard ANSI S3.19-1974, with an NRR (Noise Reduction Rate) of 33dB (highest grade) and SNR 38dB. These are earplugs that can withstand professional use. They have been tested and certified by a prestigious US laboratory, and their excellent noise reduction effect quickly leads to deep sleep. They also provide the same effect during work and study. 【2022 Newly Developed: Black Earplugs and Transparent Cord】 Earplugs with a cord are less likely to be lost, and can be hung around the neck when removed, allowing for immediate reuse. The black earplugs are less likely to attract attention, and the transparent cord is also difficult to notice. These color schemes make them less noticeable when worn, making them ideal for working or studying in cafes. The cord of this product is 70cm long. This length has been adjusted to be optimal when worn around the neck. It also reduces tangling of the cord due to excessive length. The transparent cord is designed to minimize friction noise with skin and clothing. s31-12-19