Neat little spiral pattern, not much else to it. The d10s don't spiral, sadly.
The large variant of this die is 30mm, while the small is 22mm to match the rest of the set.
Others in this set:
D4
D4 (bottom edge)
D6
D8
D10 (ones)
D10 (tens)
D12
D12 (rhombic)
D20
Basic set