Shakti Stones are 6.5"x5.5"x1.5" and filter EMI, Microwave, and RF interference. In the past one way they have been used is under and on top of components. More recently Alan Maher discovered they can provide major improvement in sound if taped to home power panels. I tried Alan's suggestion and over a one month period taped 2 stones to my main panel door, then 10 days later, 2 more to my subpanel door and finally I strapped 2 to the exposed cables in and out of the top of my main power panel. The improvement in sound quality has been stunning across all aspects for the entire listening band of frequencies. Ie more musical, more realistic like the music is live in your room, greater imaging and far more detail. I am so glad I put these in. Thanks Alan. They retail for $230 each. I found 2 on an Ebay store for $180 and picked up four more from a private party for $125 once I experienced the dramatic results from the first 2 that were installed. Not cheap, but I would equate them to upgrading a system component in the $5000 to $7000 range. They do take 10 to 12 days to fully settle in but big improvements are noticable in only 3 to 5 days.