Howard Leight by Honeywell Leight Source 400 Matrix? Earplugs Dispenser Refill saves time and space and the Earplugs feature a patented no roll foam that provides great comfort. Plugs have a small diameter with a smooth outer skin and offer three levels of attenuation. It blocks the harmful noises letting the voice to pass through and can be used in automotive industry, aviation and forestry, building construction, furniture manufacturing, landscaping and more.