f.a.n. Frankenstolz f.a.n. Frankenstolz Medisan Plus KS

The single most useful finding in this entire research, and it has nothing to do with the overall grade.

In Stiftung Warentest's March 2025 round, this was the only model with good lying properties for all seven body types in both back and side sleeping. It was a joint test winner at grade 2.2 "gut", at around €290.

To understand why that matters, understand what Stiftung Warentest changed in 2025. It expanded from four body types to seven — Ball, Säule, Sanduhr, Tropfen, Trapez, Schrank and Haus, covering roughly two-thirds of the German population — and tests back and side sleeping separately for each. Its own conclusion is that finding a mattress on which all body types lie well is a challenge. Fourteen mattresses under €630 were assessed in that round. One managed it.

If you share a bed with someone of a different build, this is more valuable than a better overall grade. The Ravensberger, also at 2.2, managed all body types in back sleeping only.

The construction is an Ortho-cel cold-foam core with seven zones, about 19 cm tall, made in Germany, available in H2 and H3. Retailer guidance suggests H2 below roughly 60 kg and H3 for most users — remembering that these grades are not standardised between manufacturers.

The double-jersey cover is removable in halves and washes at up to 95 °C, the highest temperature in this ranking. For anyone with dust-mite allergy, that is a genuine specification rather than a marketing line.

The gap is the density. f.a.n. does not publish the Raumgewicht of the Ortho-cel core anywhere we could find, and we will not substitute the RG 37 figure listed for the Medisan Max KS, which is a different product. That opacity is a real mark against it in a category where density determines how long the mattress lasts.

Trial period and warranty vary by retailer and are not published on the pages we checked.