Why make a set of dice with mirrored numbers? ...I don't really know. Seemed like a good idea when I thought of it.
Others in this set:
D4
D4 (bottom edge)
D6
D8
D10 (ones)
D10 (ones, alternate)
D10 (tens)
D12
D12 (rhombic)
D20
D20 Spindown
Basic set