Mattress Online Rock Hard Super Firm Foam EU King Mattress
The Rock Hard Super Firm Foam Mattress from Mattress Online does exactly what the name suggests.
- Very firm, full-height foam build
- Helps keep your spine aligned
- 100-night trial & 10-year guarantee
£424
Get the lowest price we've found
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
Mattress Online Rock Hard Super Firm Foam Mattress
More available sizes
Mattress details
Mattress
Mattress Online Rock Hard Super Firm Foam Mattress
Size
Firmness
Firm
Construction
Foam
Orthopaedic
Depth (cm)
23
Layers
Layer Details
Reflex Foam
A supportive foam that moulds to your body, which means it promotes spinal alignment and a slightly personalised feel despite the very firm surface. It's durable and resilient, holding its shape for an extended period of time.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
This size suits you if...
Consider another size if...
Similar Mattresses in This Price Range
Did you know? On Mattress Unboxed we have over 1,000 different mattresses to suit all types of sleepers. View all mattresses.
FAQ's