Komfi Serenity Comfort Reflex Mattress in a Box

Assessed from the specification published by archerssleepcentre.co.uk, captured October 2026, and from regular price comparison across our UK retail partners.

This is a firm mattress, so it suits back sleepers and anyone who likes to feel held up rather than sunk in. The reflex foam is described as hypo-allergenic, which is useful if you're sensitive to dust or bedding materials. The zipped cover comes off and can be machine washed, so keeping it fresh is easy. It's single-sided, which means there's no flipping to remember, and the rolled delivery makes it easier to get into tight hallways and up narrow stairs. Part of the foam is 100% recycled, a small plus if that matters to you. Komfi also offers a 10-year guarantee, although the retailer's page doesn't clearly attribute it to the brand.

Back sleepers
The firm feel of this 20cm foam mattress holds you up rather than letting you sink in, which suits anyone sleeping on their back.

Allergy sufferers
Hypo-allergenic reflex foam and a removable, machine-washable cover make it easy to keep fresh if you're sensitive to dust or bedding materials.

Eco-conscious buyers
Part of the foam is recycled Ecofoam, so you get a firm mattress that makes some use of recycled material.

If you prefer sleeping on a soft or medium mattress, this might not be the best choice. It's described as firm, which can feel unyielding for lighter side sleepers who want plenty of cushioning at the shoulders and hips. Komfi doesn't publish a layer breakdown, so it's hard to judge how much give the top has.

How firm is the Komfi Serenity Comfort Reflex?

It's described as firm, with firmer support than a medium mattress. That suits back sleepers and people who like a solid feel, although lighter side sleepers may find it a little unforgiving.

What sizes does the Komfi Serenity Comfort Reflex come in?

It comes in UK Single (90cm x 190cm), UK Double (135cm x 190cm) and UK King (150cm x 200cm). There's no Small Double or Super King listed, so check your bed frame before ordering.

How thick is the Komfi Serenity Comfort Reflex?

It's 20cm deep. That's a fairly standard height for a foam mattress, and it should sit comfortably on most bed frames. Komfi doesn't give a depth for each individual layer.

What is the Komfi Serenity Comfort Reflex made from?

It's a non-spring mattress made from reflex foam and Ecofoam, which is 100% recycled and re-engineered foam. The cover is a stretch knit fabric with a zip, so you can remove it and machine wash it.

Is there a trial for the Komfi Serenity Comfort Reflex?

Archers Sleepcentre offers its own 42-night comfort trial, and you need to buy a Purecare mattress protector with the mattress to qualify. There's also a 10-year guarantee, though the retailer's page doesn't clearly present it as Komfi's.