Sealy Advantage Topaz Natural King Size Mattress
The Sealy Advantage Topaz Natural is a medium-feel sprung mattress with wool fillings.
- Natural wool for a cushioned feel
- Support that holds up over years
- Medium feel suits most sleepers
£499
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Sealy Advantage Topaz Natural Mattress
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Mattress details
Mattress
Sealy Advantage Topaz Natural Mattress
Size
Firmness
Medium
Construction
Wool
Natural
Depth (cm)
27
Layers
3
Layer Details
Quilted Cover
The cover and fillings are stitched together into a patterned comfort quilt. This gives a settled, traditional surface rather than a loose, removable top.
Wool
A wool filling that adds a soft, cushioned feel. It suits sleepers who prefer natural materials and a classic sprung-mattress character.
PostureTech CS Springs
These springs respond to your body weight, targeting support at the areas where pressure is applied, which means your heavier zones get held up rather than sagging. They are twice tempered, so the steel is treated to stay resilient over time.
Layer details from mattressnextday.co.uk product page, September 2026.
Key benefits
- Real space for two: The UK king is 15cm wider than the UK double, which means room to change position without nudging a sleeping partner.
- Length for taller sleepers: At 200cm, the UK king is 10cm longer than the UK double, a genuine relief if one of you is approaching six foot.
- Support on your own side: PostureTech CS springs firm up where you press down hardest, so a heavier partner's side holds them up without dragging your side with it.
- Usable edges across the full width: EdgeGuard high-density foam runs around the sides, so early risers can slide out at the edge without the surface giving way beneath them.
- A settled, quilted surface: The wool fillings are stitched into a comfort quilt, giving a cushioned, natural-leaning feel that suits sleepers who dislike the sink of memory foam.
- Fits standard king bedding: At 27cm deep, standard king fitted sheets go on without a struggle, and a 230 x 220cm king duvet covers both of you properly.
This size suits you if...
You share the bed every night and a double has started to feel cramped, especially if one of you tosses and turns or gets up hours before the other. It also makes sense if one partner is tall, since the 200cm length gives feet somewhere to go, or if a dog has quietly claimed a share of the mattress and you want your space back.
Consider another size if...
Your bedroom falls short of the 2.7m x 2.9m we suggest for a UK king, or you sleep alone. In either case the UK double would suit you better, needing at least 2.6m x 2.8m.
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FAQ's
Is the Sealy Advantage Topaz Natural in a UK king good for couples?
Yes, and it is arguably the size where this mattress makes most sense for two. You get 75cm each for two people sharing, and the PostureTech CS springs respond to body weight where it lands, so a lighter and heavier partner each get support suited to their own side rather than a compromise between the two.
Will a UK king Sealy Advantage Topaz Natural fit in my bedroom?
The mattress is 150 x 200cm, or 5ft x 6ft 6in. We suggest a room of at least 2.7m x 2.9m so you can walk round both sides and open drawers. New build master bedrooms can be deceptive: measure with the wardrobes in place, as a room that looks generous empty often tightens up quickly.
Is the UK king Sealy Advantage Topaz Natural long enough for tall sleepers?
At 200cm long, the UK king gives you 10cm more length than the UK double, which is the difference between feet hanging over the end and feet on the mattress for anyone approaching six foot. If length is your main reason for upgrading, the UK king delivers it without demanding the floor space of a UK super king.
Does the UK king help with partner disturbance on this mattress?
It helps more than you might expect. The extra width means you are less likely to be touched by a turning partner in the first place, and the springs target support where pressure is applied, so movement on one side transfers less to the other. Yes, a sprung build carries some motion, but the EdgeGuard sides let early risers exit at the edge cleanly.
Where can I buy the Sealy Advantage Topaz Natural in a UK king?
Compare the retailers listed on this page. The prices shown here are updated as retailers change them, so it is worth checking back before you commit, as king sizes are often the first to be discounted during sale periods.