Silentnight Airmax 300 Mattress Topper reviewed

The Silentnight Airmax 300 Mattress Topper is a 3cm dual-layer hollowfibre topper with air-mesh sides, rated medium by Silentnight and priced from £50 for a king. It is the slimmest model in the Airmax range, meant to refresh a mattress rather than transform it.

Construction

The Silentnight product page describes the same Airmax principle as the deeper models, with mesh side walls and a dual-layer hollowfibre fill, at 3cm deep.

What a 3cm topper can and cannot do

At 3cm, the Airmax 300 is too thin to make a mattress noticeably softer. It adds a light layer of cushioning and keeps the surface cool, which suits back and front sleepers who already like their mattress. Heat is worth keeping down: a review by Okamoto-Mizuno and Mizuno (2012) linked heat exposure with more wakefulness and less deep sleep.

Sizes and prices

Prices are Silentnight’s regular prices, checked in September 2026. Single and double appear in the product data but could not be ordered, so we list it in king and super king only. Delivery takes 2 to 3 working days, and the elasticated straps fit any standard-depth mattress.

The oddity is price. In king size Silentnight charges more for this 3cm topper than for the 8cm Airmax, so unless you specifically want a slim layer, the deeper model is better value.

Who it suits

The Airmax 300 suits a narrow group: people who already like their mattress, want to keep it clean and cool, and do not want the bed to get noticeably taller or softer. Front and back sleepers who dislike sinking will appreciate that it barely changes the feel. For side sleepers who need more cushioning at the shoulder, the 8cm Airmax or the 10cm Airmax 1000 are better matches.

Silentnight does not describe the Airmax 300 as waterproof, so if you are buying it mainly to protect the mattress, pair it with a proper protector.