Heavenly Silver 9mm Ultra High Density Carpet UnderlayHeavenly Silver Label Ultra High Density + 9mm featuring powerwalk technology. This underlay has recently been boosted to pack in an extra 30% density, making an already excellent product even better and gives outstanding support to your carpet whilst providing an extremely high level of comfort. With excellent thermal insulation tog rating of 2. 40 and a very high sound impact reduction rating of 38 db for noise suppression, this underlay is suitable