Kallysleep acid reflux wedge pillows. Dimensions 80 x 66 x 12com. They have zipped removable covers. They each come in zipped protective bag. https://www.kallysleep.com/shop/all/acid-reflux-wedge-pillow/
One of these has been used once underneath the mattress; the other used twice - once under mattress and once on top of mattress but under a mattress protector.
Wedge pillows (Baguley M33)
This offer has been gifted to someone and is no longer available.