Typical rectangular lumbar sizes found in these listings include about 13 x 20 in, 14 x 22 in, 12 x 24 in, and 21 x 14 in, reflecting several standard lumbar shell dimensions.
Listings include both cover-only options (no insert) and fully filled pillows. When an insert is included, the fill is most often polyester (commonly listed as 100% polyester or polyester fiber).
Some rectangular lumbar pillows are listed for both indoor and outdoor use; those typically use high-performance outdoor fabrics that are water-, stain-, fade-, and mildew-resistant and often feature removable, reversible covers designed for outdoor conditions.
Most covers use a zipper closure; a smaller number use buttons or a knife-edge finish. Many listings show removable covers—especially outdoor or reversible designs—making the insert accessible for cleaning or replacement.
Typical thicknesses run roughly 4.0 to 5.5 inches across the listings, with several items near 5.0 in and one outdoor option listed at about 5.5 in.
Both types appear in the listings: some items are cover-only (no fill), while others explicitly include a polyester insert. Both cover-only and insert-included options are represented.