This well made and affordable 4-jaw self-centering chuck is an excellent addition to your mini lathe, giving you the stock holding options of a big chuck in a package that fits your machine and budget.
Standard jaw blocks will hold round or square objects from 1/8" to 1" dia.

#1 step jaws can grip either externally, from 3/8" to 1-1/4", or internally like an expanding collet from 1" to 2-1/2" dia.
#2 jaws have 1-1/2" to 2-3/8" external and 2" to 3" internal capacity.
As your turning grows beyond pens and letter openers, this mini scroll chuck will hold practically anything new that turns up. It comes with 2 adapters to fit both 1"-8 TPI and 3/4"-16 TPI nose spindles.