(Image credit: Plank)

Some people love a soft bed you can sink into, but I'm all about firm support. That's why I'm excited to see sleep brand Plank has extended its line-up with three new firm mattresses, starting from just $674 (was 898.67) . It even includes a firm bed designed for side sleepers.

The original Plank Firm and its Luxe Hybrid upgrade are among the best mattresses we've tested. They're unusual beds — being both double-sided and super firm — but they excel at what they set out to do. That's deliver a sleep surface that's firm all over to keep your entire body evenly supported.

The new collection plays around with that formula. The Essential and RX are both single-sided while the Luxe Zoned ditches non-stop firmness for targeted support. An exciting development ahead of the Black Friday sleep and mattress sales .…