I'm using an SDS Isoplatmat, which is a constrained 3 layer (3mm) powder coated aluminum mat. I bonded it to the platter using a very thin layer of Mono acoustic sealant, which is a butyl rubber monomer that never dries, skins or hardens. The combination is completely inert, allowing the dynamics in the recording to pop from a dead quiet background. Long time ago on a different table I compared the SDS to a Boston Audio Mystic Carbon mat at over 3X the price. The BAM was slightly more revealing of natural timbres in acoustic instruments but not enough for me to justify the additional cost. In all other aspects of sound it was virtually identical in performance. It's similar in price to the Achromat, a little thinner and maybe slightly heavier. Another alternative worth considering. I had to raise the platter so it lay flush with the bearing cap to make it work. I don't know if this is still an issue with post-beta Sols.