Firmness
Firm
Type
Pocket Spring
Depth (cm)
25
Number of Layers
2
Trial Period (nights)
100
Warranty (years)
5
Price Range
£265 to £515
Best Sleeping Position(s)
Certifications
Assessed from Mattress Online's published specification for this mattress, captured September 2026, and from regular price comparison across our UK retail partners.
If you sleep on your back or front and find most mattresses too soft, this is the sort of extra-firm support worth a look. The 1500 pocket springs respond to your body individually, which means firmer pushback where you're heavier and less pressure elsewhere, while steel piping around the edge helps the sides hold their shape. It's handcrafted in the UK, from a National Bed Federation approved brand, and fully recyclable at the end of its life. The 100-night trial matters here: extra-firm mattresses divide opinion, and being able to try it at home takes most of the risk out. Free delivery to most locations, with next day available on weekdays, is a genuine convenience too.
Key Features & what's inside
- 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.
Who's it NOT for?
Side sleepers, particularly lightweight ones, will likely find this too firm at the shoulder and hip. Anyone who enjoys a soft, cushioned or hugging feel should look elsewhere. This is an extra-firm mattress by design, and there's no thick comfort layer to soften the springs beneath you.
Mattress Online Rock Hard Mega Firm 1500 Pocket Mattress
Across owner reviews on the Mattress Online product page, rated 4.5 from 56 reviews, customers frequently report relief from back pain and waking without aches. Reviewers consistently describe a substantially firm, supportive surface with minimal dipping, suiting those with back complaints who want an extra-firm feel.
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How firm is the Rock Hard Mega Firm 1500 mattress?
Mattress Online rates it as extra firm. Owner reviews back this up, consistently describing a substantially firm surface with minimal dipping. It suits back and front sleepers who want solid support, although side sleepers may find it too unyielding at pressure points.
Does the Rock Hard Mega Firm mattress come with a trial?
Yes, Mattress Online offers a 100-night trial, so you can sleep on it at home before committing. That's a sensible safeguard with an extra-firm mattress, as firmness this pronounced isn't for everyone. There's also a 5-year guarantee covering manufacturing faults.
What sizes does the Rock Hard Mega Firm 1500 come in?
Six UK sizes: small single, single, small double, double, king and super king. Prices range from £265 to £515 depending on the size you choose, with the small single starting at £265.
How deep is the Rock Hard Mega Firm 1500 mattress?
It's 25cm deep, which is a fairly standard depth that most fitted sheets will accommodate. Inside that depth sit 1500 pocket springs topped with soft white fibre and compressed polyester fillings, finished with a viscose fabric cover.
Does Mattress Online deliver the Rock Hard Mega Firm mattress for free?
Delivery is free to most locations, with next day delivery available on weekdays and weekend delivery also offered. Delivery to your room of choice costs £20.00, and old mattress removal is available for £35.00.
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