Fully Tweed. The preferred OEM tube of "50s-era Fender Tweed Champ and Deluxe amplifiers, the Tungsol 6 V6 uses a geometry designed to safely handle the higher voltages found in guitar amps - plus heavier plate and grill materials.The result..better mids and bottom end while maintaining the smooth top of the Classic 6 V6"S. The Tungsol 6 V6 breaks evenly from low to high up to the neck. Blues players will love these tubes for the way they sing.