Jay-Be Flex Ultra Firm Mattress
Mattress
Jay-Be Flex Ultra Firm Mattress
Size
Firmness
Firm
Construction
Depth (cm)
21
Layers
4
Layer Details
- Advance e-Fibre. A breathable filling layer at the top of the mattress. It lets air move through the surface, which means less heat building up around you overnight.
- Rebound e-Fibre. A second breathable filling layer beneath the surface. It sits between you and the springs, adding a little resilience without softening the extra firm feel.
- High Density e-Fibre. A denser breathable filling layer above the spring core. This is where much of the firmness comes from, giving the surface its solid, supportive character.
- Open coil spring core. A sprung core providing reliable support across the mattress, with 325 springs in the king size. Open coil systems move as one unit, which means a firmer, more traditional feel than pocket springs.
Layer details from furniturevillage.co.uk product page, September 2026.
- Room to stretch on a firm surface: The UK small double is 30cm wider than the UK single, which means a lone back or front sleeper can shift position freely without teetering at the edge.
- Fits rooms a double would crowd: At 15cm narrower than the UK double, it can be the difference between a door that clears the bed and one that doesn't in a box room or studio.
- Breathable fillings in a snug space: Smaller bedrooms often run warmer, and the three e-Fibre layers let air move through the surface rather than trapping heat around you.
- A slim profile for tight layouts: At 21cm deep it sits lower than many hybrids, useful under sloping ceilings in a loft conversion where every centimetre of headroom matters.
- Practical for a firm-mattress guest room: Couples can share the 120cm width for the odd night, and the extra firm surface holds its shape well under occasional rather than nightly use.
This size suits you if...
You sleep alone, prefer a properly hard surface, and have outgrown a UK single without gaining the floor space for anything bigger. Perhaps you're furnishing a small second bedroom in a rental or holiday let, or a guest room where visiting couples stay a night or two rather than every week. Allow at least 2.4m x 2.8m of floor space and it should sit comfortably.
Consider another size if...
You share the bed every night, because 120cm is tight for two on an open coil core that transfers movement. We'd recommend the UK double instead, allowing at least 2.6m x 2.8m of room.
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Is a small double Jay-Be Flex Ultra Firm big enough for a couple?
For occasional nights, yes. The UK small double is 120cm wide, so two adults can share for a guest stay. Every night is harder to recommend here, because the open coil core moves as one unit and transfers motion, and that's more noticeable when you're close together. Nightly sharers would be better served by the UK double.
What room size do I need for a small double mattress?
We suggest allowing at least 2.4m x 2.8m for the UK small double. That leaves enough space to walk round the bed and open the door without squeezing past. If your room comfortably exceeds 2.6m x 2.8m, the UK double becomes an option, though the small double leaves more breathing space.
Is the Jay-Be Flex Ultra Firm small double good for a teenager?
It can be a sensible step up. The UK small double is 30cm wider than the UK single but the same length, so a teenager gains sprawling room without losing much floor space. One caution: the extra firm surface suits back and front sleepers, and a lightweight side sleeper may find it hard on the shoulder and hip.
How much wider is a small double than a single?
The UK small double is 30cm wider than the UK single, and the two are the same length, at 190cm. That extra width is what turns a bed you fit on into one you can spread out on, which matters more on a firm mattress like this, where you sleep on the surface rather than sinking into it.
Will a small double fit in a loft conversion or box room?
Often, yes, and it's a common reason buyers choose this size. Being 15cm narrower than the UK double, it can clear a door swing or leave standing room where a double wouldn't, and this mattress's 21cm depth keeps the bed low under sloping ceilings. Measure your usable floor against our suggested 2.4m x 2.8m minimum first.