POLYURETHANE FOAM Soft foam delivers superior long-wearing comfort and solid performance. SMOOTH, SOIL-RESISTANT SKIN Prevents dirt or other substances from accumulating on skin or entering ear canal,ideal for workers who need to block out loud noise and demand the best protection and comfort available in an earplug. Europe most-used polyurethane earplug, the 300 series earplug, offers superior noise-blocking performance in a single-use earplug.