Our precision-tooled aluminum forks won't rust or tarnish, so they'll last for years. You can choose the listed 320Hz Note E tuning fork, or order the complete set of eight, which comes with a rubber hammer and a soft protective case for easy storage. To demonstrate beat phenomena, we also offer a set of 255Hz and 256Hz forks. All of our forks are tuned to a tolerance of /- .5% tuning.