Visa/MC/Di/PayPal add 3%. AMEX and Canadian PayPal add 4%. Never mounted. The newly redesigned Silver1 and Gold1 have had their coil design reconfigured, and the effective moving mass of their generating system has been reduced by 17%. The Silver1 and gold1 models use a four piece OTL cantilever technology, ultra-high purity long crystal (UHPLC) oxygen free copper wire in the coils and Grado's specially designed elliptical diamond mounted on a brass bushing. The Gold1 model is selected from the Silver1 production run and meets higher test specifications. Approximately 5% of the production run meet these standards and become Gold1 models.