This spindle adapter (CA125) from Easy Wood Tools lets you mount smaller chucks with 1"x 8TPI inner threads onto larger lathes that have a 1-1/4'' x 8 TPI spindle. If you bought the smaller chuck and then later upgraded to a larger lathe, this adapter lets you keep on chuckin' without having to buy a larger chuck. Flats on the perimeter let you use a wrench for tightening.