My husband has tried various other brands of socks ,none of which
remotely resembled the L/XL I chose for him.
He finds Posey socks comfortable and true to advertised sizing.

50mm Underlay Mattress for Overlay Air Systems
Improve pressure care system with this 50mm underlay mattress, specifically designed to be used underneath overlay air mattresses. Ideal for alternating overlay systems, it ensures proper support and works in sync with the overlay's load limits for optimal patient care.
Key Features
• 50mm underlay designed for use beneath overlay air mattresses
• Compatible only with alternating overlay systems
• Load limit matches the overlay working limit for consistent support
• Color is indicative only, actual product may vary
• Length: 1980mm
• Height: 50mm