Spring King Ruby Ortho Extra Firm Small Double Mattress
The Spring King Ruby Ortho Extra Firm is an orthopaedic open coil mattress at the firmest end of the scale.
- Extra-firm for back & front sleepers
- Even support with less sinking
- Breathable cover helps you stay cool
£259
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Spring King Ruby Ortho Extra Firm Mattress
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Mattress details
Mattress
Spring King Ruby Ortho Extra Firm Mattress
Size
Firmness
Extra Firm
Construction
Orthopaedic
Open Coil Spring
Depth (cm)
27
Layers
3
Layer Details
Cover
A breathable Belgian damask fabric cover. The breathability helps air move away from your body, which means you are less likely to overheat.
Comfort Fillings
Soft white fibre fillings made from 100% polyester. These add a little softness over the springs, though the overall feel remains extra firm.
Support System
A traditional open coil unit built from one continuous high tensile spring formed into a lattice. This spreads support evenly across the mattress, which means a stable, uniformly firm surface underneath you.
Layer details from mattressnextday.co.uk product page, September 2026.
Key benefits
- Room to spread out alone: At 30cm wider than the UK single, you can sleep on your back with arms out, and the extra firm surface stays level right to the edges you roll towards.
- Fits rooms a double crowds: Being 15cm narrower than the UK double, the UK small double can leave just enough floor for a door to swing clear or a wardrobe to open.
- Firm support for a growing frame: A teenager who has outgrown a single and sleeps on their back or front gets a stable, hard base that resists the dips softer budget mattresses can develop.
- Sensible for a guest room: For visiting couples who stay a night or two, the UK small double gives them a proper shared bed without giving the whole spare room over to it.
- Breathable cover in a small space: The Belgian damask cover lets air move away from your body, which helps in a snug box room where warmth tends to build up overnight.
This size suits you if...
You sleep alone on your back or front and want more width than a single, your bedroom is compact enough that a standard double would crowd the door or furniture, or you're furnishing a spare room where couples stay only occasionally.
Consider another size if...
You share the bed every night, as the open coil passes movement across a narrow surface. We'd recommend the UK double instead, allowing at least 2.6m x 2.8m.
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FAQ's
Can two people share the Ruby Ortho in a UK small double?
For the odd night, yes. Night after night, it gets harder: open coil units tend to move as one, so on a 120cm wide mattress you'll feel your partner turning. If you share every night, the UK double gives 67.5cm each for two sharing and suits couples better, provided your room allows at least 2.6m x 2.8m.
Will a Spring King Ruby Ortho small double fit in a box room?
Often, yes. We suggest a room of at least 2.4m x 2.8m for the UK small double. The mattress measures 120 x 190cm, so measure from the wall to where your door swings and check the frame's outer dimensions too, as a chunky headboard or footboard adds to the space the bed takes.
Is a 4ft extra firm mattress a good upgrade for a teenager?
It can be, if they sleep on their back or front. The UK small double is 30cm wider than the UK single, which gives a growing teenager room without taking over a small bedroom. Lighter teenagers who sleep on their side may find the Ruby Ortho too hard on the shoulders and hips, though.
Is the Ruby Ortho small double long enough for a tall person?
The UK small double is 190cm long, the same length as the UK single and UK double. If your feet already reach the end of a standard bed, the UK king is 10cm longer, though it needs a room of at least 2.7m x 2.9m by our guidance.
Ruby Ortho small double or double for a spare room?
If guests are mostly single visitors with the occasional couple, the UK small double saves 15cm of width and needs a room of at least 2.4m x 2.8m. If couples stay regularly, choose the UK double, as the extra firm open coil feels less shared when there is more width to spread across.