Pentode vs. Triode
In guitar amplifiers most power tubes are pentodes. Pentodes have five electrodes, while triodes have three electrodes
The Yellow Jackets® pentode versions provide more bite and attitude, while the triode versions provide greater power reduction and more linearity.
If you are looking for power reduction and response with more bite and attitude, choose the pentode version. If you're looking for maximum power reduction and want to tame the response of your amp, then go for the triode version.