I don’t publish durometers of the materials I use so this is coming from an unverified source and is not an accurate representation of SquarePegToys®. One reason I don’t state them is that durometer is just one physical attribute that contributes to a material’s softness and so durometer alone can be misleading. Another reason is that my toys are all made with function as the primary focus, not the perceived softness, and I’ve found that I can achieve the proper range of functionality with only two basic firmnesses.
SuperSoft is a term I coined back in 2006 when I was the first one to introduce using a soft squishy silicone to make toys with, calling it “SuperSoft Bronze”. It is so uniquely SquarePegToys® that the copper color used to identify it has been granted trademark protection. Since then there has been a lot of other “SuperSofts” come on the market, some of which aren’t very soft at all. So when someone says their SuperSoft is a shore A 4 it can only be applied to that manufacturer, and if someone other than the actual toy maker is grading the softness I would take their measurements with a bit of doubt. Measuring durometer requires expensive instruments that need fine calibration and the expertise to use them in the correct way.