18 x 18 x 1.5 : Ergo21 Lumbar Support Cushion - Better Than Gel, Foam, and Air! Liquid-Filled Membranes. Blood Flow Improved by 150%

BlissTrends Seat Cushion with Velvet Cover, Thick Memory Foam Cushions for Office Chair, Car Seat, Airplane, Relieving Pressure Tailbone Sciatica Back Pain for Long Sitting, Car Drivers 4.7in Black

CushZone Office Chair Seat Cushion, Cooling Gel Enhanced Memory Foam Chair Cushions for Long Sitting - Back, Sciatica, Coccyx, Tailbone Pain Relief Pillow - for Office Chair, Gaming Chair, Car Seat

Socket Seat - Memory Foam Sit Bone Relief Cushion for Butt, Lower Back, Hamstrings, Hips, Ischial Tuberosity

Eder Care Doctor Recommended Premium Orthopedic Foam Coccyx Seat Cushion for Tailbone Pain Relief, Sciatica Pain Relief Hip Support, Lower Back Support with Removable Cover, Blue, Pack of 1