Yup, here's proof:
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So, I'd like elitekeyboards to post the durometer of the soft-landing pads. My guess is that the gray soft-landing pads have a durometer of about 30A and the blacks of 20A; in any case they are both softer than the 40A o-rings by wasdkeyboards.
So, the pads are a great product for people that like a really soft landing. However, to me the soft-landing pads would be greatly improved if they reduced the hole diameter to 5mm so they would stick to the keycaps both for ease of installation and to avoid the keycap stems potentially rubbing against them on every keypress.
In the case of the landing pads, they're a sponge material, so they have a different grading scale, then say a Shore A or Shore D durometer test. So I only have specs for compression-deflection (C/D), which is preferred, since durometer scales differ for material, and a durometer reading is a point reading that doesn't necessitate notable deflection nor does it take non-uniformity into consideration, whereas C/D requires the material be compressed 25% of it's height.
The "Soft" pads are 1.6mm, the C/D is about 48kPa. The "Firm" pads are 1.5mm, the C/D is about 76kPa. (So there, now anyone can copy them:)
The reason the hole diameter is what it is, is so you can get them off. During testing, when the hole was too small you needed a tweezers or long fingernails to get the pads off, particularly on the taller keycaps. So I tried to make the hole just big enough that it shakes off, but that it will kind-of hang inside the keystem, so as not to rub the keystem much, even so, I think the friction rubbing would cause is negligible in comparison to the force of your finger. Of course such tolerance in cutting a sponge material is difficult, so some fall off easier than others even when cut with the same tool. There are all kinds of other materials I had planned to play with, and maybe even redesigning the tool to have a circular cut while maintaining the pull-off sheet design, but I'm on to more exciting (and hopefully profitable) R&D at the moment, so it will have to wait.