Jay-Be Flex Ultra Firm E-Pocket 1200 Mattress in a Box
Mattress
Jay-Be Flex Ultra Firm E-Pocket 1200 Mattress in a Box
Size
Firmness
Construction
Depth (cm)
21
Layers
3
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.
- Fits where other beds won't: At 90cm wide, it leaves room for a desk, wardrobe or toy storage in a child's bedroom without the bed dominating the floor.
- Suits raised frames: The 21cm depth sits comfortably within the safety rails of most bunks, cabin beds and mid sleepers, where a taller mattress would ride too high.
- Light enough to move solo: A single is the easiest size to rotate, carry upstairs or shift between rooms, useful for student flats and guest rooms that get rearranged.
- Two singles beat one double for guests: In a spare room that hosts different combinations of people, a pair of UK singles is more flexible than a single larger bed.
- Firm support in a starter size: An ultra-firm sprung core under foam-free e-Fibre layers gives back and front sleepers proper resistance, which few boxed singles offer.
This size suits you if...
You sleep alone and want a firmer surface than most boxed mattresses provide, you're buying for a child or teenager whose room has to fit a bed alongside everything else, or you're kitting out a spare room, bunk bed or student flat where a slim, easy-to-handle mattress makes life simpler. Allow at least 2.1m x 2.8m of floor space and it will fit almost any UK bedroom.
Consider another size if...
You share the bed regularly, or you're a broader adult who finds 90cm restrictive when turning over. We'd recommend the UK double instead, which is 45cm wider than the UK single and the same length; allow at least 2.6m x 2.8m for it.
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Will the Jay-Be Flex Ultra Firm UK single fit a bunk or mid sleeper frame?
It's a strong candidate. At 90 x 190cm it matches the standard UK single frames used for bunks, cabin beds and mid sleepers, and the 21cm depth is slimmer than many hybrids, so it shouldn't sit above the safety rail. Do check your frame's maximum mattress depth before ordering, as raised beds vary.
Is the UK single Jay-Be Flex Ultra Firm a good choice for a child's room?
On space, yes: at 3ft wide it leaves room for storage and a desk, and we suggest a minimum room of just 2.1m x 2.8m. On feel, be aware this is a genuinely ultra-firm mattress. Children who like a soft, sink-in surface may find it hard, so match it to how your child actually sleeps.
How much bigger is a UK double than this UK single?
The UK single is 45cm narrower than the UK double, and the two are the same length. If a solo sleeper wants more room to spread out, the extra width is the whole story. For the UK double we suggest a room of at least 2.6m x 2.8m, against 2.1m x 2.8m for the UK single.
Is the UK single long enough for a tall adult?
It measures 3ft x 6ft 3in, so most adults fit, though taller sleepers may want their feet clear of the end. The UK single is 10cm shorter than the UK king, which is where the extra length sits in the range. If length is your concern, that's the size to compare.
Where can I buy the Jay-Be Flex Ultra Firm in a UK single?
Compare the retailers listed on this page. The prices shown here are updated as retailers change them, so it's worth checking back rather than relying on a figure you saw last week. Stock in individual sizes can shift more often than the model as a whole.