Grado Blue3 5.0 mV output Two Channel Prestige Cartridges are Available in P-Mount Version The newly redesigned Blue1 and Red1 have had their coil design reconfigured, and the effective moving mass of their generating system has been reduced by 17%. The Blue1 and Red1 models use a four piece OTL cantilever technology, standard oxygen free wire in the coils and Grado's specially designed elliptical diamond mounted on a brass bushing. The Red1 model is selected from the Blue1 production run and meets higher test specifications. Approximately 10% of the production run will meet these standards and become Red1 models.