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.

Configura Comfort Black Profiled Headrest
The top cushion of the Waterfall Backrest can be removed and replaced by the profiled headrest, which offers increased support for the service user’s head.
Suitable for all size Configura Comfort Chairs
Suitable for users with reduced head control
Fabric: Black VP
Suitable for use with all Configura chairs