SWATCOM SC21 Pro Impulse are reusable ear plugs designed to reduce loud noises to safe levels. The ear tip design provides a comfortable and discreet fit, and instead of blocking noise which leads to a muffled sound, the filter reduces noise levels allowing you to hear both safely and clearly. The Pro Impulse filters provide a constant 15dB (SNR) reduction, but can react to sudden loud noises to provide a brief higher level of protection before returning to the normal constant level.