Who makes Horizon Mattresses? The Horizon mattresses are a sub-brand created by Mattress Online, launched back in 2018 as a means of being able to offer affordable, high quality pocket spring mattresses with a mass amount of fillings. Some of the mattresses in this range have over 10cm of memory foam as a topper which means you can get a medium-firm tension mattress that will be great for your back pain while also managing to offer a mass amount of comfort. Are Horizon Mattresses any good? Reviews for Horizon mattresses are still rolling in but everything so far suggests that these mattresses are perfect for a wide array of body types, pains and sleeping positions. The reviews are generally 5 stars from enough users to confidently recommend. The memory foam comfort layer works especially well with the pocket spring bases to create the perfect harmony between comfort and support.