Real-life (not accelerated aging) tests have revealed that some CD-Rs degrade quickly even if stored normally.[8][9] The quality of a CD-R disc has a large and direct influence on longevity—low quality discs should not be expected to last very long. According to research conducted by J. Perdereau, CD-Rs are expected to have an average life expectancy of 10 years.[10] Branding isn't a reliable guide to quality, because many brands (major as well as no name) do not manufacture their own discs. Instead they are sourced from different manufacturers of varying quality.