Sealy Harlow Ortho Plus Mattress
The Sealy Harlow Ortho Plus is a firm orthopaedic mattress, handcrafted in the UK and sold exclusively through Mattress Online.
- Firm feel for back & front sleepers
- Fibre top cushions hips & shoulders
- 100% recyclable at end of life
£314
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At 26cm deep, the Sealy Harlow Ortho Plus pairs Sealy's PostureTech Core Support Springs with soft white fibre fillings under a damask cover, which means a supportive, fairly traditional feel rather than the sink-in hug of memory foam. It's single-sided, so there's no flipping required, and it comes in five UK sizes from Single to Super King. Mattress Online lists a 100-night trial and a 5 year guarantee, which gives you a decent window to decide whether that firmer feel suits you.
Mattress specifications
Firmness
Firm
Type
Orthopaedic
Depth (cm)
26
Number of Layers
2
Trial Period (nights)
100
Warranty (years)
5
Price Range
£314 to £589
Best Sleeping Position(s)
Back Sleeping
Stomach Sleeping
Certifications
BS 7177
Assessed from the specification published by Mattress Online, captured September 2026, and from regular price comparison across our UK retail partners.
Why should you choose this mattress?
If you sleep on your back or front and want firm support at a sensible price, this is the sort of mattress to shortlist. The PostureTech Core Support Springs use varied tensions and unique shapes, which means different parts of your body get support matched to the pressure they place on the mattress. A layer of soft white fibres sits above the springs to cushion hips and shoulders, so it's firm without feeling bare. It carries reassuring credentials too: National Bed Federation approved, fire resistant to BS7177: 2008, and 100% recyclable at the end of its life. Yes, it's a simpler build than pocket sprung or hybrid designs, but that simplicity keeps the starting price down.
Key features & layer details
Comfort Layer
Soft white fibre fillings sit at the surface to cushion the hardest parts of the body, which means your hips and shoulders get a little give before reaching the firmer support below. It's a traditional filling with a slightly springier feel than foam.
Support System
PostureTech Core Support Springs use unique shapes and varied tension across the mattress, which means fuller support where your body presses hardest and pressure relief where it doesn't. This is the layer doing most of the orthopaedic work.
Layer details from mattressonline.co.uk product page, September 2026.
Best suited for?
Back sleepers
The firm feel and PostureTech Core Support Springs give matched support across the body, which means your back stays well supported without sinking in.
Front sleepers
Firm support from the varied tension springs helps keep your middle from dipping, while the soft white fibre layer adds a little cushioning on top.
Budget buyers
A simpler build than pocket sprung or hybrid designs keeps the starting price down, so you get firm, traditional support at a sensible cost.
Guest rooms
Being single-sided, there is no flipping to remember, and the 100-night trial and five UK sizes make it easy to fit into a spare room.
Lightweight side sleepers may find a firm orthopaedic feel too unyielding on the shoulder and hip. Across owner reviews, some mention concerns about edge support, so if you sit on the side of the bed a lot, that's a weak spot. And if you love a deep, cradling memory foam feel, this isn't it.
Save on an earlier or ex-display model
Some retailers still sell the earlier version of this mattress, or ex-display and returned stock at a lower price. These are the sizes where it costs less than the current model's best price.
Sealy Harlow Ortho Plus Mattress
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FAQ's
Is the Sealy Harlow Ortho Plus firm?
It's listed as firm, and it's an orthopaedic design, so expect a supportive feel rather than a soft one. That said, some owners in reviews found it a little softer than they anticipated, so the fibre comfort layer does take the hard edge off.
Does the Sealy Harlow Ortho Plus come with a trial?
Mattress Online, the retailer that stocks it exclusively, lists a 100-night trial and a 5 year guarantee. These are the retailer's own terms rather than a Sealy promise, so check the details at checkout.
Do you need to flip the Sealy Harlow Ortho Plus?
No. It's a single-sided mattress, so there's no flipping required, which is welcome given firm orthopaedic mattresses can be heavy to handle.
How deep is the Sealy Harlow Ortho Plus mattress?
It's 26cm deep, a fairly standard depth that should work with most fitted sheets without any struggle.
What sizes does the Sealy Harlow Ortho Plus come in?
Five UK sizes: Single, Small Double, Double, King and Super King.
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