Slow-recovery PVC foam provides comfort with low pressure. - Soft polymer foam expands in the ear for a custom fit. - Will not absorb moisture and swell. Maintains comfort, fit and recovery. - Classic Plus Earplugs are longer and can be inserted deeper into the ear canal for greater noise reduction. - Box of 200 corded pairs. - Classic has an NRR of 29 dB, while the Classic Plus has an NRR of 33 dB. - CSA class A(L).