The RM Metal is based on the British Range Master unit produced between 1965 and 1969, as used by Eric Clapton in John Mayall's Bluesbreakers. It's equipped with the same OC44 germanium transistors as the the original 1965 version. The RM Metal is a modified '69er RM model like Mr. Iommi's unit, which he used on the second and later Black Sabbath records. The RM Metal model is recommeded for nu-metal, low dropped tunings and baritone guitars.
The booster is true bypass and can powered only by battery. The BSM full guarantee periods are 1 year for all mechanical parts, including the switch, pots, jacks etc., and 3 years for the electronics. BSM stompboxes are built like tanks and should last forever.
For more information, visit their web site at www.treblebooster.net.