Golden Voice Tubes KT88+.
This uses materials and processes from high-end products for a more consistent quality.
KT88 is a beam power tetreode, its anode limited dissipation power is 42W. In the audio amplifier, the power can be 100W when it is used as push-pull class AB1 with double tubes, it can also be used in electronic voltage regulator circuit. KT88 is similar with CV5220 and 6550,they can be replaced by each other.