Impact Gravity or KH trials unicycle?

It’s prob from several parts:
TR pedals are pretty light (332 g),
Tensiles (140mm) are a fair amount lighter than Moments [410 g vs 612 g (the newer KH’s are lighter)]
lighter tire w/ the directional tread
the cut foam of the seat would save a few grams

and he may be using a thinner/smaller tube than you.
crank weight thread