Branded Valvo
Round Tip
- Base
- Black
- Bottle Height
- Tall Bottle
- Bottle Shape
- Skinny Bottle
- Code On Tube
- Xf2 B7B4
- Country
- Great Britain
- Factory Code
- B - Mullard, Blackburn, B - Mullard, Blackburn, B - Mullard, Blackburn
- Getter
- O-O Double Getter
- Getter Support
- Double
- Glass Color
- Clear Glass
- Mica
- Double
- Permanentid
- hst4sqna
- Pin Color
- Silver
- Plate Color
- Matte Gray
- Plate Look
- Weld
- Tip Shape
- Round Tip
- Year
- 1957
