Mattress Online Rock Hard Mega Firm 1500 Pocket Super King Mattress
The Rock Hard Mega Firm 1500 Pocket Mattress does exactly what the name suggests.
- Extra-firm for back & front sleepers
- Handcrafted in the UK, fully recyclable
- 100-night trial & 5-year guarantee
£474
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Mattress Online Rock Hard Mega Firm 1500 Pocket Mattress
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Mattress details
Mattress
Mattress Online Rock Hard Mega Firm 1500 Pocket Mattress
Size
Firmness
Firm
Construction
Pocket Spring
Orthopaedic
Depth (cm)
25
Layers
2
Layer Details
Comfort Layer
Soft white fibre fillings, finely filled with high density compressed polyester. This gives a thin layer of cushioning over the springs, which means you'll feel comfort at the surface but firmness underneath rather than a plush, sink-in feel.
Support System
1500 pocket springs that gently contour around your body for personalised support. Because each spring moves independently, you get support matched to your shape and less motion transfer if you share the bed.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- 90cm of firm surface each: Two people sharing get 90cm each, which means you can both lie flat on your back, the position this mattress is built for, without touching.
- Restless partners fade into the distance: The 1500 pocket springs move independently to limit motion transfer, and at this width there's simply more mattress between you and a fidgeting partner.
- Room for children and dogs: When a child wanders in at 3am, a UK super king absorbs the extra body without anyone retreating to the edge, and the firm surface stays supportive across its full width.
- Steel piping across a wide edge: Edge support matters more on a 180cm-wide mattress, and the steel piping helps the long sides hold their shape when you sit or sleep near them.
- A step up from the UK king that you'll feel: The UK super king is 30cm wider than the UK king, which works out at 15cm more space each, roughly the difference between sharing and sleeping separately together.
This size suits you if...
You share the bed every night and want to stop noticing your partner's movement, you have children or a large dog who treat your bed as theirs, or you have a larger master bedroom where a UK king would look and feel undersized. You should also prefer a properly firm surface, because the extra space doesn't soften what is, by design, an extra-firm mattress.
Consider another size if...
Your bedroom is smaller than the 3m x 2.9m we suggest as a minimum, or you sleep alone. We'd recommend the UK king instead: it's 30cm narrower, still gives couples 75cm each, and needs at least 2.7m x 2.9m.
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FAQ's
Is the Rock Hard Mega Firm 1500 super king good for couples?
Yes, provided you both like a firm feel. Across the UK super king's 180cm width, two people get 90cm each, and the 1500 pocket springs move independently, so one person turning over sends little movement across the bed. It's divisive on comfort: side sleepers of any size may find it too solid at the shoulder.
How much bigger is the super king Rock Hard Mega Firm than the king?
The UK super king is 30cm wider than the UK king, and the two are the same length at 200cm. For couples, that's 15cm more space each: the UK king gives 75cm per person, the UK super king 90cm. If a restless partner or visiting children are the problem, that extra width does more than any comfort layer could.
What room size does the Rock Hard Mega Firm super king need?
We suggest at least 3m x 2.9m, with around 3.5m x 3.2m feeling comfortable once you add bedside tables and walking space on both sides. In a loft conversion, the sloped ceiling usually decides which wall a bed this size can sit against, so measure head height as well as floor space.
Can two people of different weights share the super king Rock Hard Mega Firm?
The pocket springs respond to each sleeper individually, giving firmer pushback where you're heavier, so a mismatched couple each gets support suited to their build. The overall feel stays extra firm for both of you, though. A lighter side sleeper is likely to find it too hard at the hip whichever half of the UK super king they take.
Is the Rock Hard Mega Firm super king difficult to get upstairs?
It can be. This is a one-piece pocket spring mattress, 180cm wide and 200cm long, and it won't compress or fold the way some foam mattresses do. Before ordering, measure your stairwell, any landing turns and the bedroom door swing. Mattress Online doesn't publish a weight for this size, so check the brand's own guidance if lifting is a concern.