Really sensitive and change colour easily. The "cool" colour is awesome (black + gold glitter) but rapidly changes through some gorgeous oranges, greens, purples and blues. easily and quickly changes colour in your hand (except when your are on camera and trying to show someone how cool the dice are...)
C H O N K E R is well worth it, beautiful and makes a lovely thud to scare your players with.
Don't underestimate the normal D20 though. It tries to compete with the fear of the CHONKER by teaming up with the other dice to try to murder your players (nat 20s abound! Then of course rolling the d6 4X for damage on a level 3 party you'll get many 6s and nothing below 4). brutal.