These fibres are produced environmentally friendly, mainly from used PET bottles which are collected, sorted, cleaned, granulated and re-melted and spun. These fibres require high-quality raw materials due to their predominant use for foodstuffs. Minor impurities often reduce the whiteness of the fibres when compared with virgin fibres. They therefore have limitations concerning dying. Their technical specifications also have greater tolerances than virgin quality fibres. They also are available as hollow and mass-dyed fibers. This quality of fibre was originally produced only for filling and insulation material with titers of 6,7 dtex or coarser, but they are now also available from 1.7 dtex.