High NRR plugs deliver superior noise-blocking performance. Contoured bell-shaped design provides an excellent ear-canal fit with enhanced back-out resistance. Soft, expanding polyurethane foam ensures a comfortable fit. Smooth, soil-resistant closed-cell foam skin protects against dirt buildup. Leight Source 500 Refill. Corded/Cordless Pair: Cordless; Shape: Bell; Material(s): Polyurethane Foam; Noise Reduction Rate (NRR): 33 dB.