Firmness
Type
Memory Foam
Depth (cm)
27
Number of Layers
4
Trial Period (nights)
Warranty (years)
5
Price Range
£429 to £749
Best Sleeping Position(s)
Certifications
Assessed from the specification published by MattressNextDay, captured September 2026, and from regular price comparison across our UK retail partners.
If you like the pressure-relieving hug of memory foam but worry about sleeping hot or feeling stuck, the spring core here helps, allowing more airflow and bounce than a solid foam slab. The PostureTech springs are twice tempered, which means the steel is heat-treated twice so the springs keep their shape and support for longer. EdgeGuard reinforcement around the springs also firms up the sides, so you can sit or sleep near the edge without that roll-off feeling. Available in five UK sizes from Single to Super King, with prices ranging from £429 to £749, it's a sensible choice for a family home where different rooms need different sizes.
Key Features & what's inside
- Quilted Cover. The cover is stitched together with the fillings to create a patterned comfort quilt, which means the surface has a soft, cushioned feel built in rather than a flat top. It's the first thing you'll notice when you lie down.
- MemorySense Foam. This memory foam layer adapts to your body position, cocooning you and easing pressure at the shoulders and hips. In practice, that means less tossing and turning to get comfortable.
- PostureTech CS Springs. These springs respond to your body weight to give deep-down support, so heavier areas get more pushback than lighter ones. They're twice tempered, meaning the steel is heat-treated twice to stay resilient over years of use.
- EdgeGuard. A high-density foam strip reinforces the springs around the perimeter, extending their lifespan. You'll feel this as a firmer, more supportive edge, useful if you sit on the bed or share it and need the full width.
Layer details from mattressnextday.co.uk product page, September 2026.
Who's it NOT for?
If you prefer a plush, sink-right-in surface, the Medium Firm rating here may feel a touch too solid. Committed hot sleepers should also think carefully: the springs help with airflow, but memory foam does hold more warmth than latex or open coil designs. And if you want a lengthy home trial, none is mentioned on this listing.
Sealy Advantage Quartz Memory Mattress
How firm is the Sealy Advantage Quartz Memory Mattress?
It's rated Medium Firm. That means a supportive feel with a softer, quilted memory foam surface on top, a balance that suits most back and side sleepers, although lightweight side sleepers may find it slightly firm.
Does the Sealy Advantage Quartz come with a guarantee?
The MattressNextDay listing states a 5-year guarantee on this mattress. There's no trial period mentioned on that page, so check the terms with your retailer before buying if a sleep trial matters to you.
How deep is the Sealy Advantage Quartz mattress?
It's 27cm deep, which fits standard UK fitted sheets comfortably. That depth comes from the quilted cover, memory foam layer and spring unit combined.
What sizes does the Sealy Advantage Quartz come in?
Five UK sizes: Single, Small Double, Double, King and Super King, priced from £429 to £749 depending on size.
Is the Sealy Advantage Quartz made in the UK?
Yes. It's made in the UK and Sealy is an NBF-Approved Manufacturer, which means the National Bed Federation has audited what goes into the mattress and how it's made.
Couldn't find an answer to your question? Send us a message