Open Coil (Bonnell)
By Kaiser Khan, Editor Updated First published
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In short
An open coil mattress uses one linked grid of springs, not separate pockets. The Bonnell spring is an hourglass-shaped coil tied to its neighbours with wire. Because the coils share the load, movement travels across the bed more than in a pocket sprung unit. Open coil mattresses often cost less to make.
About 1 minutes to read
Definition. An open coil is a mattress spring unit where hourglass-shaped springs are linked by wire into one grid, so they move together.
The linked grid spreads weight across the whole unit. That makes it feel even, but a partner turning over is easier to feel.
Open coil mattresses often cost less than pocket sprung ones. Read the wire gauge and the padding on top to judge the feel.
Full guide: open coil and Bonnell spring systems. Also: pocket sprung vs open coil.