3M™ Peltor™ X Series X4 Earmuffs, X4B, behind-the-head. Details:•Design of neckband allows earmuffs to be worn with a variety of face shields and headgear•Compatible with headgear without accessory slots•Soft, adjustable head strap helps to maintain a secure fit with many different types of headgear•Fit can be confirmed: Verify with 3M™ E-A-Rfit Dual-Ear Validation System•Comfortable to wear even with other protective equipment•Noise Reduction Rating (NRR) of 27 dB, CSA Class AL3M™ Peltor™ X Series Earmuffs help keep your hearing protected while you're on the job. Comfort, design and protection all come together in this versatile earmuff line. The design of the neckband allows earmuffs to be worn with a variety of face shields and headgear. These earmuffs have a Noise Reduction Rating (NRR) of 27 dB and CSA Class AL.