The original RASCO system used filters made from stick PVC fly screen mesh wound around a centre core encapsulated by an outer sleeve. This method of trapping odours onto fly screen was a tried and tested method taken from the trials in South Africa in the 90s and is still used today in Europe.
REST filters adopted in the UK are made from a porous fibre material encapsulated in a plastic bar coded sleeve and placed in an air tight security sealed container. They are less labour intensive to manufacture and work in exactly the same manner.
REST filters are made under licence by a third party in controlled conditions, to ensure the quality and consistence of the filters.
In 2010 trials were done using cloth samples to trap odours from the back of traveling DHL vehicles. These cloth samples were put into specially adapted perforated containers and REST was performed on the samples.
The trial were successful but no commercial operation was every launched. But it did prove that the REST system was the flexibility and odours could be trapped on a variety of materials.