Firmness
Firm
Type
Pocket Spring
Depth (cm)
25
Number of Layers
5
Trial Period (nights)
100
Warranty (years)
5
Price Range
£799 to £1,509
Best Sleeping Position(s)
Certifications
Assessed from the specification published by Mattress Online, captured September 2026, and from regular price comparison across our UK retail partners.
If you want firm support without the dead, board-like feel some firm mattresses have, this is a sensible shortlist candidate. The 4000-spring build combines a Cortec Quad core with two layers of mini pocket springs, which means a responsive, slightly bouncy surface rather than a rigid one. The springs sit in individual fabric pockets secured without glue, and the whole mattress is 100% recyclable and chemical treatment-free, a genuine rarity. It's hypoallergenic, National Bed Federation approved, and conforms to BS7177: 2008. Yes, it's single-sided so you can't flip it, but rotating it every 6 months keeps wear even. Mattress Online lists a 100-night trial and a 5-year guarantee, both that retailer's own terms.
Key Features & what's inside
- Quilted panel sleep surface. A quilted panel with tufting hidden on the inside of the soft fabric cover, which means a smooth sleep surface without the knots or bumps you sometimes feel through traditionally tufted mattresses.
- Enviropad filling. Three thick, fluffy layers of Enviropad filling relieve pressure build-up around your hips and shoulders. It's also fully recyclable, so the comfort layer doesn't end up in landfill.
- Cortec™ Quad pocket spring core. The main Cortec Quad core places each spring in its own fabric pocket, secured together without glue. That means each spring moves independently, giving personalised support where your body needs it.
- Posturfil mini pocket springs. 1000 Posturfil mini pocket springs add a bouncy, comforting feel on top of the core. They also improve airflow through the mattress, which helps if you tend to sleep warm.
- HD mini pocket springs. A further 2500 HD mini pocket springs provide additional bouncy comfort. This second mini spring layer is a large part of why the firm feel doesn't come across as harsh.
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Layer details from mattressonline.co.uk product page, September 2026.
Who's it NOT for?
This is a genuinely firm mattress, so lightweight sleepers, particularly side sleepers under a lighter build, may find it doesn't let their shoulders and hips sink in enough. It's also single-sided: you rotate it every 6 months rather than flip it. And if you prefer the slow, contouring hug of memory foam, this springy feel isn't that.
Harrison Spinks Quilted Fusion 4000 Pocket Mattress
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Is the Harrison Spinks Quilted Fusion 4000 firm or medium?
It's firm, according to the retailer listing. In practice the 1000 Posturfil and 2500 HD mini pocket spring layers give it a bouncy quality, so it feels supportive rather than hard. Lighter side sleepers may still find it a little too solid.
How many springs does the Quilted Fusion 4000 have?
4000 pocket springs in total: a Cortec Quad pocket spring core, plus 2500 HD mini pocket springs and 1000 Posturfil mini pocket springs. Each spring sits in its own fabric pocket, secured without glue, which means the springs respond individually to your body.
Does the Harrison Spinks Quilted Fusion 4000 come with a trial and guarantee?
Mattress Online lists a 100-night trial and a 5-year guarantee with this mattress. Both are that retailer's own terms rather than a manufacturer offer, so if you buy elsewhere, check what that seller provides before ordering.
Do you need to flip the Quilted Fusion 4000 mattress?
No, it's single-sided so it shouldn't be flipped. Instead, rotate it end to end every 6 months to keep wear even across the sleep surface. Owner reviews mention the handles make moving it easier.
What sizes does the Quilted Fusion 4000 come in?
It's available in UK Single, UK Double, UK King and UK Super King, with prices ranging from £799.00 to £1,509. The mattress is 25cm deep, so most standard fitted sheets should work without trouble.
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