Grünthaal appears once on this site, in chair floor mats, with its SilentFloor fleece chair mat.
Fabric, where the others are plastic. The Björn&Schiller, Kernburg and KLINOO are rigid clear or milky plastic; this one is a soft fleece of about 3 mm (0.12 in). Grünthaal’s claim follows from that: a chair rolls more quietly on it, and it feels warmer underfoot. At 90 × 120 cm (35.4 × 47.2 in), it is the same size as the Kernburg and KLINOO.
A base that keeps spills off the floor. The CalmGrip underside is waterproof-coated and non-slip, so a spilled drink does not reach the floor and the mat stays put. Grünthaal points it at hard floors and rental flats.
More care than plastic. Crumbs and marks come off with a vacuum or a damp cloth, where a plastic mat just wipes clean. It comes in anthracite, grey or light brown, and is marketed for the whole home — under a coffee table or exercise equipment as well as a desk chair. The listing says nothing about underfloor heating; the Kernburg is the only mat here stated safe over it.
Where to buy it. It is not listed on Amazon.com, so from the US the button opens a search.