We consider two-stage production lines with an intermediate buffer. A buffer is needed when fluctuations occur. For single-product production lines fluctuations in capacity availability may be caused by random processing times, failures and random repair times. For multi-product production lines fluctuations are also caused by different processing time ratios for different products and by set up times. We examine whether it is possible to use the results developed for single-product flow lines, where the production units have exponentially distributed life- and repair times, for the multi-product case. As an example the case of a consumer electronics factory is studied.