Thank you for viewing. This is a set of BioSonic tuning forks, 528Hz and 936Hz. I am selling them because I don't have much opportunity to use them. The mallet, bag, and English instruction manual shown in the second image are included. I have never struck the tuning forks against each other or hit them against anything hard. I have only occasionally produced sound with the mallet. There are some areas with slight discoloration. Please check the condition in the images before purchasing. As a service, a black walnut pen stand is also included. By wrapping paper around the base of the tuning fork to adjust the size, you can store the tuning fork upright. For those who need them, please consider purchasing.