This description is summarized from the manufacturer’s description at http://www.boston-audio.com/tuneplates.html
TunePlates are a unique isolation system that can be used just about anywhere in a hifi system, with or without TuneBlocks. Measuring 76.4mm (3”) square and 3mm (1/8”) high, TunePlates are ideal for tight spaces. Each TunePlate is a stainless steel and elastomer sandwich. The first layer is a thick sheet of stainless steel that’s strong enough to withstand spikes from the heaviest speakers. Next is a proprietary elastomer layer. Finally, a thinner layer of stainless steel completes the sandwich.
Use TunePlates in a variety of situations—under any footer such as TuneBlocks (including TuneBlocks S with speakers), under speaker or rack spikes, between mini monitors and stands, between speakers and the floor with speaker spikes removed, between a TuneBlock and a component or under a component’s stock footers, especially a hard footer made of aluminum, stainless steel, or carbon fiber.
One owner. Some of the TunePlates have small scratches or smooth spots from prior use. Performance is not affected.
Price shown is for one set of four TunePlates. Two sets are available. Price for both sets is $99. Price includes Paypal and shipping within CONUS. Buyer pays actual cost of shipping elsewhere or other shipping services.