1" x 10TPI Lathe Collet Chuck Portass Lathe W 7x Myford Collets 5/8" Shaft
The chuck has 1"x 10 tpi spindle thread for use on Portass lathes or similar. They have a 5/8" shank body with tapered nose. There are 7 collets, they don't say the size on (that I can see) but they all seem different sizes.