The Ruby EL34BSTR's/EL34BW are a new high gain tube developed by Ruby and manufactured by Shuguang. They have a gold plated grid and extra thick glass. Perfect for modern gain, these have unique a wall of sound break up, very articulate. Ruby Tubes are matched both by plate current and transconductance and come with a 6 month warranty. For use in applications where the plate voltage is less than 450 vdc. For higher voltages, use the Ruby EL34BHT's.