Sealy Advantage Sapphire Geltex Pillow Top King Size Mattress
The Sealy Advantage Sapphire Geltex Pillow Top Mattress combines a plush pillow top with a gel-infused Geltex comfort layer, which means a cushioned surface that eases pressure where you feel it most.
- Eases pressure where you feel it
- Support that responds as you move
- Reinforced edges for steady sides
£669
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Sealy Advantage Sapphire Geltex Pillow Top Mattress
More available sizes
Mattress details
Mattress
Sealy Advantage Sapphire Geltex Pillow Top Mattress
Size
Firmness
Medium
Construction
Gel
Memory Foam
Pocket Spring
Depth (cm)
28
Layers
3
Layer Details
Pillowtop
A plush pillow top that adds an extra layer of cushioning, which means a softer-feeling surface than the medium rating alone suggests.
Geltex comfort layer
A cushioned, gel-infused Geltex layer that relieves pressure on the parts of the body that feel it most, so your hips and shoulders get some extra give.
PostureTech CS spring system
Pocket springs that respond to shifts in body weight to give localised support, with Edge Guard foam strips inside the spring unit. You get support that follows your movements, plus steadier edges.
Layer details from mattressnextday.co.uk product page, October 2026.
Key benefits
- More room each than a double: You get 75cm each, which is 7.5cm more per person than the UK double, so elbows and knees stray across the middle less often.
- Easier for early risers: If one of you is up hours before the other, 75cm each gives the early riser room to get out along their own side without brushing past a sleeping partner.
- Length for taller partners: At 6ft 6in long, the UK king is 10cm longer than the UK double, so a partner over six foot is less likely to have their feet hanging over the end.
- Steadier edges when space runs out: Edge Guard foam strips sit inside the spring unit, which should make the sides feel more dependable if you sleep near the edge or sit there to get up.
- Cushioning across a wider bed: The pillow top and Geltex layer give a softer surface than the medium rating suggests, and on a UK king there's room to shift position without bumping into your partner.
This size suits you if...
You share the bed every night and keep ending up in each other's space on a double, one of you gets up much earlier or later than the other and you want more room between you, or one of you is over six foot and wants the extra length.
Consider another size if...
Your bedroom is smaller than our suggested 2.7m x 2.9m for a UK king. We'd recommend the UK double instead, which we suggest for rooms of at least 2.6m x 2.8m.
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FAQ's
Is the Sealy Advantage Sapphire Geltex Pillow Top in a UK king big enough for two adults?
For most couples, yes. The UK king gives 75cm each, enough for two adults to sleep without much contact. If one of you sprawls, or a dog regularly claims the middle, that space can shrink quickly, and the UK super king's 90cm each may suit you better.
How much bigger is a king size Sealy Sapphire Geltex than a double?
The UK king is 15cm wider and 10cm longer than the UK double. Shared between two people, that works out at 7.5cm more each. On paper it looks modest, yet couples moving up from a UK double usually notice it straight away, particularly in the length if one of you is tall.
What size bedroom do I need for a UK king Sealy Advantage Sapphire?
We suggest a room of at least 2.7m x 2.9m for a UK king. Measure after wardrobes and drawers are in, because a new build master bedroom can feel much smaller once furniture is in place. Check your stairs and doorways too, then compare the retailers listed on this page.
Should we choose the UK king or UK super king Sealy Sapphire Geltex Pillow Top?
The UK super king is 30cm wider, giving 90cm each against the UK king's 75cm. Both are 200cm long. If bumping into each other is your main complaint and your room allows at least 3m x 2.9m, the UK super king gives more space between you. Otherwise the UK king suits most couples well.
Is a king size Sealy Sapphire Geltex long enough for someone over 6ft?
The UK king is 200cm long, or 6ft 6in, which is 10cm longer than the UK double. For a partner over six foot, that extra length is often the real reason to size up, since it leaves room for a pillow at the top without feet reaching the end.