These small pom poms are made with raw silk threads.  They are used to set the gold or other metallic powder after sprinkling and powdering.  Especially with keshi-type (matte finish) powder, buffing the powdered surface lightly in circular motion gives it a slight sheen. 
 
Some artisans also use the pom-pom to apply keshi-type powder directly onto cured lacquer surface.  SImilar to ladies powdering their faces with cosmetic dry-powder.  
 
Each one is hand-tied so sizes varies.  They last for a long time.  With small kintsugi repair, the smaller the pom-pom, the better control, and less waste in gold powder.   You can also re-shape it to the size of your preference.  
 
Using one pom-pom for one kind of powder.  Suggest storing them separate if used on different color powders so they would not contaminate your dusting.   
 
PRODUCT OF JAPAN