Our 4", 4-Jaw Easy Chuck™ features the Easy Jaws™ System with patented Snap-Lock Technology SLT™ allowing 30-second jaw changes, with no screws to lose. The patented Zoom Ring™ allows for fast one-hand adjustments. Rounded safety corners on the jaws reduce injuries. Hardened and plated components inside and out that are machined to high tolerances, make the Easy Chuck™ strong and durable for a lifetime of use. Available in four body sizes: 1" X 8 TPI, 1-1/4" X 8 TPI, M30 X 3.5 and M33 X 3.5. Standard equipment includes 1-3/8" Dovetail Easy Jaws™, patented Easy Chucking Screw with 3/8" & 1/2" double-ended design, T-Handle jaw lock hex key, and ball end jaw releases hex key. Made in the U.S.A. 
US Pat No. 9,370,826 (Easy Chuck); US Pat No. D753,477 (Easy Chucking Screw)