The Simba Natural Hybrid Source is a 28cm foam-free mattress of British and Hampshire wool over up to 2,900 springs.
The Simba Natural Hybrid Source is a foam-free 28cm mattress built from British and Hampshire wool around one layer of Aerocoil microsprings and a seven-zone steel base, for up to 2,900 springs in a king. It is the entry model of Simba’s Natural Hybrid range, rated medium-firm (6 out of 10 on our scale), with a regular price from £899 for a single.
Eight layers and no foam, according to Simba’s UK product page. Spring counts are for a king.
| Layer | Material | What it does |
|---|---|---|
| 1. Cover | Plant-derived viscose, invisible tufting, bio-based fire retardant | Smooth sleep surface |
| 2. Cushioning | Quilted Hampshire wool | Soft, springy top |
| 3. Comfort | Quilted British wool | Comfort and breathability |
| 4. Cushioning | Hampshire wool | Resilience and airflow |
| 5. Support | Thick British wool | Support above the springs |
| 6. Microsprings | Up to 1,900 titanium-alloy Aerocoil springs, made in Leeds | Pressure-relieving, low motion transfer |
| 7. Stability | British wool | Stability and breathability |
| 8. Base | CoreMax, up to 1,000 high-carbon steel barrel springs in seven zones, made in Hampshire | Support to the edge, reinforced frame |
Wool buffers moisture and lets air through, which is the case Simba makes for the range. The provenance is checkable. Simba says the wool is farmed in the UK or is Hampshire wool sourced under the Traceable British Wool Scheme, and British Wool states that it can trace every bale back to the farm, grading fleece into one of 100 grades at eight UK depots. The Source is crafted in the UK and delivered flat.
Sleepers who want natural fillings and a supportive, medium-firm feel. A systematic review of 24 trials in Sleep Health (Radwan et al., 2015) found medium-firm, self-adjusted mattresses optimal for comfort, sleep quality and spinal alignment; the medium-firm feel suits back sleepers and most side sleepers. The single microspring layer makes it firmer than the plush Apex. Its single costs the same as a Hybrid Pro single, so the choice between them is wool against foam rather than price.
The trade-offs come with the fillings. The cover is not removable, so Simba strongly recommends a protector; the mattress must never be vacuumed, and it should be rotated head to foot every couple of months for the first six months, then twice a year.
| Size | Dimensions (cm) | Regular price |
|---|---|---|
| Single | 90 x 190 | £899 |
| Double | 135 x 190 | £1,299 |
| King | 150 x 200 | £1,399 |
| Super king | 180 x 200 | £1,599 |
Regular prices at the time of writing (September 2026). Delivery is Simba’s free VIP service with installation, followed by a 200-night trial and a 10-year guarantee.
| Brand | Simba |
|---|---|
| Material | Plant-derived viscose cover with invisible tufting, quilted Hampshire and British wool layers, a thick British wool support layer, up to 1,900 titanium-alloy Aerocoil microsprings, a British wool stability layer and a seven-zone CoreMax base of up to 1,000 high-carbon steel barrel springs. No foam. |
| Made in | United Kingdom |
| Firmness | Medium firm (6/10) |
| Height | 28 cm |
| Sleep trial | 200 nights |
| Warranty | 10 years |
| Delivery | Free VIP delivery, delivered flat |
| Available sizes | 90x190, 135x190, 150x200, 180x200 |
| Overall score | 8.2/10 |
“The Natural Hybrid Source is our pick for sleepers who want wool and springs without foam at the lowest price in Simba's natural range, from the same price as a Hybrid Pro single. Choose the Apex only if you want a noticeably plusher top, because the Source's single microspring layer makes it the firmer of the two.”
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