ST Pro! I mod'd mine up to better than a stock premium for lots less than a Premium. Play is just as good. Colored playfield inserts give richer color than RGB and clear inserts. Get Aurich translate and decals if possible. Color LCD, shaker motor for sure. Zits pop bumper caps and Pinblades, Vengeance explosion light and visor kit and Cliffy's on the plastic ramps are must haves! Install v1.62 with movie sound code! Tron is stupid expensive!