What Raul said. I just added the AT mat to my Micro Seiki turntable, replacing a pure copper platter. The build quality of this item is beyond my expectations for a "tweek" platter mat. It is solid, not too heavy, "dead" and precisely engineered. I wouldn't characterize the benefit as earth shattering, but it does improve playback. If it matters, the price is easy on the wallet. As Raul said, this item is out of production, so the challenge is finding one to buy. I have owned a few TTs, and looked at many platter mats. Most look like toys compared to the Audio Technica.
