Mutt Muffs-Colour Red. SKU DDRRed Over-the-Head Hearing Protector for Animals. Specially Designed Wide Foam Filled Ear Seals for Maximum Comfort. Engineered specifically to properly meet the contour of a dog's head Comfortable and Lightweight Adjustable Straps for Optimum Fit. Inner sound-deadening foam is the same density found in pilot's high-end headsets Made entirely in the United States of America The inner foam that is used is the exact same ester resin foam that is used in many high end commercial head sets designed for humans. Based on the materials used, the estimated decibel reduction is between 21 and 24, assuming proper fit and a good seal against your pup's head. That's 21-24 dB reduction in the human hearing range of 20,000 cycles per second, which is the only range that we have data for. Our canine friends can hear much higher frequencies (in the range of 43,000 cycles per second). As the frequency goes up, so does the effectiveness of Mutt Muffs, simply because the higher the frequency is, the more easily it is absorbed. Therefore, Mutt Muffs are especially effective at protecting against the high frequency wind whistles and shrieks we humans cannot even hear. There is another factor that comes into play as well. The dog's own ear flaps are down and covering the ear canal, providing yet another layer of protection, better even than placing your hands over your own ears. Mutt Muffs are designed not to block out all sound, but to be a passive, noise reducing device that will make a ride in the airplane or in a noisy environment a comfortable experience for your mutt. The overall circumference measurement of your dog's noggin at the largest point is the best determination of size, because if you choose a size too large, the muffs won't seal well against his head, and you lose all the sound-reducing properties you were shooting for. Your dog's weight is also a good indicator of which size to choose.