First off, I’m not an expert, I’m just a guy who poured mold-making silicone gel on the deck of my boat a couple of days ago, in order to capture the surface detail to re-create it after making repairs. The cured mold is definitely the same sort of rubbery feel as the gel wrist rest I’ve owned, just firmer. According to the ScienceDirect article, the basics are all the same: It’s a matrix of loosely-linked silicone elastomer molecules, but the final product can vary a lot depending on the amount of cross-linking, and the amount of fluid infused in the matrix. That ultra-soft product that you linked, like the mold-making stuff that I used, probably has dyes in it for user-friendliness. (To know when you’ve mixed the two parts thoroughly.) That means the product won’t be clear. Also, I think the wrist rests may have some sort of polymer (vinyl?) outer layer for durability. That would make it look a little different.