13mm Drill Chuck - #1 MT
Jacob Style Drill chuck 13mm chuck with no. 1 Morse taper
Morse Taper #1.
Morse taper #1 is commonly found on small (mini) or older lathes.
The large end of a Morse Taper 1 (MT#1) is approximately 12mm
If your tailstock spindle has a taper and is approximately 12mm in diameter then this is probably the correct one for you.