There are numerous spring systems available on the market, with the premium beds using individual heat tempered springs, which greatly reduce partner disturbance and eliminates roll together.
All Sleepyhead springs units are heat tempered.
Premium mattresses will also offer targeted support to hip and shoulder regions.
In the mid price range, most beds use inner spring support systems. The most advanced of these systems use continuous heat tempered wire springs, which are linked head to toe to help prevent roll together.
Cheaper beds generally use spring systems where springs are linked across the bed, and in some instances increase roll together. These beds won't give the life of more advanced spring systems.