Kingnex Adjustable Firmness Bolster Roll Pillow for Under Knee Support or Between Legs for Side Sleepers, Shredded Latex Cylinder with Removable Cooling Cover 18x6 Review (2026)

Purpose and sizing

This bolster is sized at 18 inches long by 6 inches in diameter, a compact cylinder meant specifically for placement under the knees or between the legs rather than as a full-length body pillow. Side sleepers commonly use a roll like this to keep the top knee elevated and the hips aligned, which can ease pressure on the lower back compared with sleeping with the legs stacked directly on top of each other. Because it is a small, focused roll rather than a long body pillow, it is not designed for hugging or supporting the torso, so shoppers looking for a full-length companion pillow should look at longer body pillow options instead. The 18x6 size also makes it easy to carry between rooms or pack for travel compared with bulkier body pillows.

Fill material

Kingnex fills this bolster with shredded latex rather than memory foam, and latex as a material tends to sleep cooler and feel more responsive and bouncy than memory foam, which can feel denser and slower to spring back. The shredded format, rather than a single molded latex core, allows the fill to be adjusted, and the cover's zipper gives access to remove or add latex pieces to change how firm or soft the roll feels under the knee. This adjustability means two people with different firmness preferences can each tune the same style of bolster to their own comfort level rather than being stuck with one fixed density. Latex fill is a meaningful consideration for anyone with a latex sensitivity or allergy, since direct or prolonged contact with latex material could be an issue for those individuals.

Cooling cover

The outer cover is designed to feel cool against the skin and is removable via a zipper, separate from the inner liner that holds the shredded latex in place. Being able to remove and wash just the outer cover keeps the bolster fresh without having to handle the loose latex fill directly, which is more practical for regular laundering than pillows without a removable cover. The cooling cover complements the latex fill's naturally cooler feel compared with memory foam, so the combination is aimed at sleepers who run warm and want to avoid a hot, dense pillow pressed between or under the knees through the night.

Who it suits

This bolster is best suited to side sleepers dealing with knee, hip or lower back discomfort who want a small, targeted support piece rather than a large body pillow to manage. It also works for people who simply prefer keeping their knees slightly separated and supported while sleeping on their side, which can reduce strain on the lower hip through the night. Because of its compact size, it is a reasonable secondary pillow to add alongside a regular head pillow rather than a replacement for one, and its portability makes it a candidate for travel if you rely on knee support to sleep comfortably away from home.

Care and adjustability

The removable cover can be unzipped and washed on its own, which is the main maintenance most owners will need to do regularly. The shredded latex fill inside is best kept dry and out of a washing machine, similar to how shredded memory foam fill is typically handled, since machine washing loose fill risks clumping or damaging the material. Adjusting the firmness is straightforward: unzip the inner liner, remove or add shredded latex pieces, and reseal it to reach the desired density, which means the bolster can be softened over time if it feels too firm out of the packaging or firmed back up if it packs down with use.

Frequently asked questions