Sealy Harlow Ortho Plus Small Double 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
£589
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Sealy Harlow Ortho Plus Mattress
More available sizes
Mattress details
Mattress
Sealy Harlow Ortho Plus Mattress
Size
Firmness
Firm
Construction
Orthopaedic
Open Coil Spring
Depth (cm)
26
Layers
2
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.
Key benefits
- Real width for one sleeper: At 120cm across, the UK small double is 30cm wider than a UK single, which means a solo adult can change position freely on this firm surface.
- A double feel in a compact room: It's 15cm narrower than a UK double, so a box room or studio keeps its walkway while you keep a bed two people can share occasionally.
- Firm support that suits spreading out: The PostureTech Core Support Springs vary their tension across the mattress, which means the extra width stays evenly supportive rather than firm in the middle and soft at the sides.
- Standard 4ft bedding and frames: The small double is an established UK size, so fitted sheets and bed frames are easy to find, unlike some in-between widths.
- Sensible for guest rooms: A firm feel with soft fibre cushioning tends to divide people less over a night or two, which makes this size a practical guest room option.
This size suits you if...
You sleep alone and have outgrown a UK single but can't spare the floor space a UK double demands, you're furnishing a guest room where couples stay occasionally rather than nightly, or you're kitting out a small second bedroom in a rental or holiday let and want a firm mattress that most visitors will find agreeable.
Consider another size if...
You share the bed every night and 120cm of width feels like a squeeze for two. We'd recommend the UK double instead, which is 15cm wider and the same length; allow at least 2.6m x 2.8m of room for it.
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FAQ's
Is the Sealy Harlow Ortho Plus small double big enough for two adults?
For occasional nights, yes. At 120 x 190cm it works for couples staying in a guest room or sharing now and then. For every night, two adults will feel the limited width, and lighter side sleepers may notice the firm feel more when they can't spread out. The UK double gives 15cm more width.
Will the small double Sealy Harlow Ortho Plus fit in a box room?
In most cases, yes, and that's the main reason to choose it. We suggest a room of at least 2.4m x 2.8m, which leaves space to walk round and open the door. If your room clears that comfortably, the UK double needs at least 2.6m x 2.8m, so measure before ruling it out.
Is a small double or single better for a teenager?
If the room can take it, the UK small double is the better long-term buy. It's 30cm wider than the UK single and the same length, so a growing teenager gets room to sprawl without the bed eating more of the floor lengthways. The firm orthopaedic feel here suits back and front sleepers in particular.
How much space does one person get on this size?
The whole 120cm of width is yours, which is a noticeable step up from a UK single and enough for most solo adults to stretch out properly. Some owner reviews of this mattress mention edge support as a weak spot, so having that extra width to sleep away from the sides is a genuine plus.
Where can I buy the Sealy Harlow Ortho Plus in a small double?
This mattress is sold through a limited number of retailers, and stock in each size changes. The prices shown on this page are updated as retailers change them, so compare the retailers listed here for the current small double price rather than relying on a figure you saw elsewhere.