Groove Tubes GT-6L6-R(B): Russian made, very sturdy and reliable tube. Perhaps the most reliable of the currently made types, with slightly less power and a more aggressive edge when pushed into distortion.

Groove Tubes GT-6L6-R(B) tubes are used by Fender in amps that use 6L6 tubes and are amps that DO NOT come from their custom shop. These are used in the Hot Rod series, Blues DeVille series, Pro Tube series, BF reissue series.