Spring King Ruby Ortho Extra Firm Super King 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
£439
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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
- Space to absorb movement: Open coil units pass movement across the bed, so the 90cm each you get in a UK super king puts real distance between you and a partner who turns over often.
- 15cm more each than a UK king: Sizing up from the UK king adds 15cm of personal width per sleeper, which means a fidgeting partner is far less likely to end up on your side.
- Room for small visitors: When a child pads in at 3am, 180cm of width means both adults can keep sleeping rather than one of you retreating to the edge or the sofa.
- Firm enough for a heavy dog: A large dog sleeping on the bed as routine will sink in less on an extra firm surface, and the UK super king leaves you both room to stretch out.
- Fills a large master bedroom: In a period property or generous master, a UK king can look a little lost, whereas a UK super king sits in proportion with high ceilings and wide walls.
- Same length as a UK king: The UK super king matches the UK king's 200cm length, so taller sleepers gain width without losing any legroom compared with the next size down.
This size suits you if...
You share the bed with someone who tosses and turns and you both want a genuinely firm surface, children or a dog regularly join you overnight, or your bedroom comfortably clears our suggested minimum of 3m x 2.9m.
Consider another size if...
Your room is smaller than 3m x 2.9m, or you sleep alone. We'd recommend the UK king instead, which needs at least 2.7m x 2.9m and still gives 75cm each for two.
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FAQ's
Is the Ruby Ortho super king good if my partner is a restless sleeper?
It helps a great deal, though the credit goes to the width rather than the springs. The single continuous coil tends to carry movement across the whole bed, so what protects you is the 90cm each that a UK super king provides. That is 15cm more per person than the UK king.
Can two adults and a child fit on a Spring King Ruby Ortho UK super king?
Yes, for the odd night visit. At 180cm wide, a small child can lie between two adults without anyone hanging off the edge. The extra firm surface also means the middle stays level instead of dipping, although a child used to a softer bed may find it a little hard at first.
Should I get the Ruby Ortho in a UK super king or a UK king?
Choose the UK super king if your room allows at least 3m x 2.9m and one of you moves a lot at night. It is 30cm wider than the UK king and the same length. If space is tighter, the UK king needs at least 2.7m x 2.9m.
Will a UK super king Ruby Ortho fit in a loft conversion bedroom?
Only if the sloping ceiling leaves a full 180 x 200cm of floor with enough headroom along one wall. Measure where you can actually stand, not the total floor area. Then check the door swing and every landing turn on the way up, because a 27cm deep mattress this wide is awkward to angle round tight corners.
Is an extra firm super king a good idea if only one of us likes a hard bed?
Probably not. The Ruby Ortho has one feel across its full 180cm, so a UK super king cannot be softer on one side. A lighter side sleeper is likely to find it hard on the shoulders and hips, however much room they have. It suits couples who both prefer firm support.