Firmness
Type
Pocket Spring
Depth (cm)
21
Number of Layers
3
Trial Period (nights)
Warranty (years)
10
Price Range
£261 to £450
Best Sleeping Position(s)
Certifications
Assessed from JAY-BE's published specification for this mattress, captured September 2026, and from regular price comparison across our UK retail partners.
Choose this if firmness is your priority. Jay-Be describes it as ultra-firm, and the construction backs that up: a densely packed Firm e-Fibre comfort layer over an ultra-firm sprung core, so you sleep on the mattress rather than sinking into it. It's also a strong pick if you want to avoid foam. The e-Fibre layers are made partly from recycled PET bottles, the fabric is OEKO-TEX certified, and the fire retardant treatment is a natural salt-based one rather than a chemical spray. Jay-Be backs it with a 10-year guarantee, and delivery is free next working day when you order before 12pm. Back and front sleepers who find most mattresses too soft will feel most at home here.
Key Features & what's inside
- Advance e-Fibre™. A deep-quilted top layer of Advanced e-Fibre, which gives the sleep surface a softer first impression than the name ultra-firm might suggest. It also wicks moisture, which means better temperature regulation through the night.
- Firm e-Fibre™. A densely packed comfort layer that delivers a firm feel with some pressure relief. This is where the mattress earns its firmness rating, sitting between you and the springs.
- Ultra-Firm Sprung Core. The support layer, engineered for stability that lasts. It keeps the mattress from softening into a dip over time, which means consistent support night after night.
Layer details from jaybe.com product page, September 2026.
Who's it NOT for?
Side sleepers, especially lightweight ones, will likely find this too firm at the shoulder and hip. If you prefer a cushioned, sink-in feel, look elsewhere: ultra-firm means exactly that. The 21cm depth may also feel shallow if you're used to a taller, more hotel-style mattress.
Jay-Be Flex Ultra Firm E-Pocket 1200 Mattress in a Box
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How firm is the Jay-Be Flex Ultra Firm E-Pocket 1200?
Jay-Be rates it as ultra-firm, and the build reflects that: a firm e-Fibre comfort layer over an ultra-firm sprung core. There's a softer quilted surface layer on top, but this is a properly firm mattress, best suited to back and front sleepers who want minimal sinkage.
Does the Jay-Be Flex Ultra Firm mattress contain foam?
No. The comfort layers use Jay-Be's e-Fibre material, made in part from recycled PET bottles, over a pocket sprung core. The fabric is OEKO-TEX 100 Standard certified and the fire retardant treatment is a natural salt-based one.
How deep is the Jay-Be Flex Ultra Firm E-Pocket 1200?
It's 21cm deep. That's slimmer than many hybrid mattresses, which makes it a tidy fit for guest beds, bunk-friendly frames and standard fitted sheets, although it won't give you the tall, plush profile some people prefer.
What guarantee comes with the Jay-Be Flex Ultra Firm mattress?
Jay-Be offers a 10-year guarantee, according to its own site. Delivery is free next working day when you order before 12pm, and the mattress arrives rolled in a box.
What sizes does the Jay-Be Flex Ultra Firm come in?
Four UK sizes: Single, Small Double, Double and King. Prices range from £261 to £450 depending on the size you choose, starting from £261.63.
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