The 6AL5 miniature all glass envelope houses two separate signal diodes and the 6058 is the special quality version. Brimar use the term Trustworthy.
The usual requirement in special quality valves was the ability to work reliably in areas of vibration such as aircraft.
These diodes were specifically designed for vision and sound detection in television receivers. Additionally they are recommended for limiting and DC restoration.
If this is trustworthy what are the commercial valves?.
Two tiny diodes separated by a sheet screen.
This valve is 18 mm in diameter and 46 mm high excluding the B7G base pins.
References: Data-sheet & 1040. Type 6058 was first introduced in 1951. See also1951 adverts.