To use in the headstock as a turning chuck, you first turn a spigot on the piece and then put the spigot in the chuck. For drilling, it can be used in either the headstock or the tailstock.
The 1/2" three-jaw chuck is available with either a #1 or a #2 Morse taper (MT) adapter (drilled and tapped for a 1/4-20 restraining rod, not included). Please check your lathe specifications for Morse taper size before ordering.