The 6060 is the special quality version of the ECC81 VHF double triode. It is useful for RF stages, oscillators and frequency multipliers, but the construction is slightly different to the ECC81.
The envelope carries three Type designations: 6060, CV4024 & 12AT7WA. The box also carries the Type E81CC.
Normally special quality valves have double micas to reduce the effects of vibration. This has a single mica top and bottom.
The envelope carries the words Made in UK indicating that not all Zaerix valves were made in Eastern Europe.
The box anodes are folded to provide two flanges that are stitched together.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 49 mm long.
References: Datasheet & 1040. Type 6060 was first introduced in 1951.