Please note at the time of purchase 5-Jan-13, the inserts sent were 1cm at the thickest point, and not 2cm as per dimensions in the technical details section for the item. In saying that, the 1cm turned out to be fine for me.
I do a lot of running and have in the past used in store moulded trainer insoles to support my arches, which suffer on longer runs. The moulded insoles cost around £40 to have made. I thought I would test these out, for £2.39 it was worth a try.
Even though they are silicone, they were a bit hard when used directly to support my arches (when running). I ended up putting them underneath the insoles that came with the trainers to provide a cushioning layer. This has worked really well, an arch support for a fraction of the price of moulded insoles. Will definitely buy another set when I need replacements.