Mattress inner spring unit, which is very popular in the worldwide., especially in North America and Central America. With various series, such as 252, 312, 336, 364, 522, 660...in Twin size, Full size, Queen size, King size and so on.

For the bonnell spring,
4 turns, height range 85mm - 105mm
5turns, height range 135mm - 150mm
6turns, height range 145mm - 170mm

Steel wire range, 2.1mm -2.4mm

Helical wire range, 1.3mm or 1.4mm

Border wire range, 4.0mm -5.0mm

What's more, we can make other special size according to your detailed requirements.