This complete assembly includes the North Eastern Arms stock adapter (with screw) and Tapco M4 style 6 position stock (includes castle nut). All the parts needed to mount this collapsible stock to the rifle.
The M4 stock is positioned higher with this adapter (higher than the original vz.58 wood impregnated buttstock and the original Czech side-folding stock) and is best used with an optic. Iron sights can still be used, but some people have reported that the M4 stock is too high for a comfortable cheek weld.