Here is a description of the transistor that is available on this page, see the Sun Face page for all of the transistor options:

RCA/BART Hybrid : We use an RCA low transistor to avoid temperature instability, and a BART high transistor to make the sound fatter and fuzzier. They still clean up well, all along the volume pot range, not too fast. A little brighter than all BART. These are medium gain, maybe Mike's favorite transistor option.

Here are descriptions of the options that this pedal comes with:

LED: lights up when on - doesn’t suck much battery power ;)

Power Jack: Necessary if you do not want to power by battery or easier if you want to use a virtual battery. Traditional Fuzz players always used a battery for optimum tone - Many players use a power jack now and do not find a huge difference in tone/sound. If you get the power jack you will have the option of powering by battery or by any Boss style 9V DC Isolated power supply. Having the power jack installed does not change the tone of the pedal.

Sun Dial Knob: Very useful on germanium pedals, especially med to high gain. Will give you different tones/sounds when turning and can be adjusted if the temperature gets hot. Will give you different tones/sounds when turning and can be adjusted if the temperature gets hot. Not terribly useful on silicons and can introduce noise in higher gain silicon fuzzies. You can use the internal (usually black) BIAS trimpot to change the bias on any of these, if you have the sundial it's a rough bias control to set the center of the Sun Dial knob. You can turn the bias down for a spittier sound with less sustain.