Start with the type. Ear muffs to EN 352-1 go on and off quickly and are easy to check from a distance, which suits workers who move in and out of noisy areas: Delta Plus offers the MAGNY COURS 2, INTERLAGOS and SPA 3, and Karam the Classic, Foldable Deluxe, High dB Foldable and Frontier. Ear plugs to EN 352-2 are small, cool in hot weather and sit comfortably under other PPE: disposable polyurethane foam plugs come from Delta Plus (CONIC500, with the CONIC DISPLAY dispenser for walls or benches) and Karam (EP01 uncorded, EP02(A) corded), and Karam's EP03(M) and EP04(M) three flange plugs are washable and reusable. Where hard hats are worn, helmet mounted muffs to EN 352-3 fix to the helmet: the Delta Plus MAGNY HELMET 2 fits ZIRCON, QUARTZ, GRANITE and BASEBALL DIAMOND helmets, and the Karam Helmet Attachable Ear Muffs snap on and off.
Then match the rating to the noise. SNR is the single number rating under EN 352, and Delta Plus also gives NRR under ANSI S3.19 and H, M and L values for high, medium and low frequency noise. Among the muffs, the SPA 3 is rated SNR 23 dB, the Karam Classic and Frontier SNR 27 dB, the INTERLAGOS SNR 30 dB, the MAGNY COURS 2 and Karam Foldable Deluxe SNR 33 dB, and the Karam High dB Foldable SNR 34 dB for heavy industrial noise. Disposable foam plugs reach SNR 36 dB (CONIC500) and SNR 34 dB (Karam), Karam's reusable plugs SNR 30 dB, and helmet mounted muffs SNR 30 dB (MAGNY HELMET 2) and SNR 25 dB (Karam). Aim to bring the noise at the ear down to a safe level without blocking so much that workers miss alarms, vehicles and speech.
Finally check comfort and the site. Weights differ: SPA 3 155 g, Karam Classic 180 g, Foldable Deluxe 230 g, helmet attachable muffs 260 g and High dB Foldable 305 g, and Karam describes the Frontier as very light. Karam's foldable muffs pack into a pocket or storage bay to stay dust free, the Frontier is dielectric and metal free for work near electricity, and the INTERLAGOS comes in grey, fluorescent yellow or fluorescent orange for high visibility. Corded plugs stay together around the neck, Delta Plus lists the CONIC500 for ear canals of 7 to 12 mm, and Karam's foam plugs and helmet muffs are also ISI marked to IS 9167:1979.