Kirafy makes two products for people who sleep on their side.
Cloudspan — support for the shoulder-to-neck gap
Its contoured profile is shaped around the space between the shoulder and neck, with a fixed pillow height and room for the shoulder.
Keel — room for the top arm and knee
Its curved body-pillow shape gives your top arm and knee somewhere to rest while you lie on your side.
For both pieces together, see The Complete Set.