The SparkPlugs NRR 33dB is the highest independently tested NRR available. Their random fun-colors are a great way to put some spark in your hearing protection program. They're the perfect way to let your employees show their love for NASCAR racing. Their extra-soft, extra-light foam and tapered design seal gently and snugly without pressure, while the outer surface is smooth, so it doesn't irritate the ear canal. Bright, fun colors provide easy compliance checks and are 100% PVC-free. SparkPlugs are available in uncorded (M6604) and corded (M6654). Earplugs are colored bright orange, purple and green. The bright green color is a trademark of Moldex-Metric, Inc. The random color patterns are a registered trademark of Moldex-Metric, Inc. NASCAR is a registered trademark of the National Association for Stock Car Auto Racing, Inc. The NASCAR trademarks are used under license by the National Association of Stock Car Auto Racing, Inc.