Shungite Tumble Stones 

Shungite has metaphysical properties that make it useful for balance and protection. It helps you focus on goals as it acts as a conductor of energy and moves it towards your desired outcome. It is considered a cleansing stone that purifies the body, mind, and spirit. 
Shungite is a very popular EMF neutraliser. 
Tumbles are 2-3cm - size & shape varies as Mother Nature decides