1、2 Sets Clamp Jaw: The tired chuck has 3/32in to 1‑7/8in external clamping range and 11/32in to 3‑3/8in internal clamping range, while the round chuck 1‑1/2in to 3‑1/8in external clamping range and 2in to 3‑7/8in internal clamping range. 2、Premium Material: Mainly made of premium alloy steel material, the lathe chuck is not likely to deform and very sturdy for long term use. 3、Standard Threads: Including 1in x 8TPI spindle adapter, the 4in chuck also has M33 x 3.5 thread for stable and reliable working. 4、Wide in Utility: Suitable for lathes, grinders, milling machines, drilling machines, machine tool accessories, woodworking machinery, etc. 5、Easy to Install: Comes with a compact size and a light weight as well, the 4 jaw lathe chuck is very convenient to install within minutes.