BHaving read much of your site, i asked the manufacturer 'Bed Company Wales' what was inside his 6000 series zip and link mattress, and hs reply is below. It comes with a sprung base and zipped both sides for full rotationPocket spring unit based on a 1200 count spring1200g needled cotton ( each side )1200g layered cotton ( each side )900g wool ( each side )Can you give me a compatible model in your range of beds and what would I expect to pay ?