Jay-Be Flex Ultra Firm E-Pocket 1200 Mattress in a Box
The Jay-Be Flex Ultra Firm E-Pocket 1200 is a boxed mattress built for people who want genuinely firm support, not the medium-firm feel most brands settle on.
- Ultra-firm for back & front sleepers
- Foam-free with recycled fibres
- 10-year guarantee
£261.63
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At 21cm deep, the Jay-Be Flex Ultra Firm E-Pocket 1200 is slimmer than many hybrids, which means it suits divans, bed frames and guest beds without towering over them. The feel comes from an ultra-firm sprung core topped with two layers of Jay-Be's e-Fibre, a foam-free comfort material partly made from recycled PET bottles. It comes in UK Single through to UK King. Yes, ultra-firm is a niche feel, but if that's what your back needs, few boxed mattresses commit to it this clearly.
Mattress specifications
Firmness
Extra Firm
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)
Stomach Sleeping
Certifications
OEKO-TEX, Global Recycled Standard
Assessed from JAY-BE's published specification for this mattress, captured September 2026, and from regular price comparison across our UK retail partners.
Why should you choose this mattress?
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 & layer details
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.
Best suited for?
Back sleepers
A densely packed Firm e-Fibre layer over an ultra-firm sprung core keeps you on top of the mattress rather than sinking in.
Front sleepers
Sleeping on the mattress rather than sinking into it suits those who find most beds too soft, thanks to the ultra-firm sprung core.
Eco-conscious buyers
The e-Fibre comfort layers are made partly from recycled PET bottles, and the fire retardant treatment is natural and salt-based rather than a chemical spray.
Guest rooms
At 21cm deep, it is slimmer than many hybrids, so it sits neatly on divans and bed frames without towering over them.
Warm sleepers
The deep-quilted Advanced e-Fibre top layer wicks moisture, which helps regulate temperature through the night and keeps the foam-free surface feeling fresher.
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.
Save on an earlier or ex-display model
Some retailers still sell the earlier version of this mattress, or ex-display and returned stock at a lower price. These are the sizes where it costs less than the current model's best price.
Jay-Be Flex Ultra Firm E-Pocket 1200 Mattress in a Box
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FAQ's
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.
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