The Volas Inflatable Lumbar Reliever, Adjustable Air Bag Waist Support Plate to Relieve Lumbar Disc and Waist Stretching Artifact Wholesale listing includes customizable air-filled lumbar support.
The usable photo shows a raised centre under an arch. The page does not name a hand pump or a PSI. Use any in-box inflate steps. Stop if the plate feels unstable.
Read the Volas lumbar details.