The #3 Smooth Jaws for the Stronghold Chuckare great for turning large vases and bowls (over 12" in diameter and 5" deep). #3 jaws are an asset because their larger size will better support your material, whether holding inside or out.
Why Oneway Jaws are Superior
Most jaws on the market are designed to only fit one diameter by a limited depth (design diameter). For example, a set of jaws turned to 2" diameter with a 7° taper * 1/4 deep will only work well in a cavity that is exactly 2" diameter * 7° and just less than 1/4" deep. They will hold progressively less, and increasingly damage your mounting as this base size changes from the theoretical perfect size.
Oneway jaws are designed to achieve excellent 8-point contact at all diameters in the jaw size range.Their patented profile top jaw shape increases gripping power at all diameters of round and square stock. Less wood damage also occurs with this jaw shape than with the conventional round-shaped jaws.
Carbon steel base jaws provide precision grinding on the sides for the exact and controlled clearances, which are required for woodturning chucks
Base jaws are case hardened which makes them longer lasting, stronger, and non-seizing in use