The bottom of the block is coated with a gel thermal pad. This will help to form into the crevices on the bottom of hard drives and improve thermal conductivity between the copper block and the hard drive itself. Theoretically, it would be possible to replace this with a non-conductive thermal paste like Artic Alumina. However, as we will see during testing, the included thermal pad does a significant job of reducing hard drive temps as is, so Cooler Master have obviously done their homework on this one.