3M Peltor ear defenders, in both electronic and passive form. Which you need depends on whether you have to hear anything between shots.
Electronic or passive
Electronic muffs use microphones to pass quiet sound through at normal volume while clamping down on the muzzle blast. That means you can hold a conversation on a peg, hear a dog, or hear a beast moving in thick cover — and still be protected when the shot comes. The Sport-Tac (SNR 26dB), the ProTac Hunter and the ProTac Shooter are all this type. For stalking and driven days they are worth the money.
Passive muffs simply block. The Bullseye III does the job perfectly well on a clay ground or a zeroing range where you do not need to hear anything, and costs a good deal less.
Fit beats rating
An SNR figure assumes a proper seal. Long hair, spectacle arms and a high jacket collar all break that seal, and a muff worn over any of them protects far less than the number on the box suggests. If you wear glasses, check the seal with them on.
For children
The Kid muffs come in pink and neon yellow, the yellow rated SNR 27dB. Anyone standing behind the line needs protection as much as the gun does, and children's hearing damage is permanent.
More options in hearing protection, and do not forget eye protection.
