1008 Folding Stock (folded with penalties)
1009 Retractable Stock (retracted with penalties)

1008 Folding Stock (unfolded, no penalties except for small CTH penalty)
1009 Retractable Stock (extended, no penalties except for small CTH penalty)

1745 Folding Stock (folded with penalties)
1746 Folding Stock (built-in, unfolded, no penalties except for small CTH penalty)
1747 Folding Stock (built-in, folded with penalties)
1748 Retractable Stock (retracted with penalties)
1749 Retractable Stock (built-in, extended, no penalties except for small CTH penalty)
1750 Retractable Stock (built-in, retracted with penalties)

Item 1008 transforms into 1745 and vice versa.
Item 1009 transforms into 1748 and vice versa.
Item 1746 transforms into 1747 and vice versa.
Item 1749 transforms into 1750 and vice versa.