These vises have rugged, machined, double guide rods and single-lead Acme screws.
The regular front vise is 7" x 14-3/4" overall with a 7/8" dia. screw and clamping capacity of 8-1/4" (less the thickness of your wooden jaws).
Our large front vise is 10-1/2" x 21" overall with a 1-1/8" dia. screw, and 13" clamping capacity (less the thickness of your wooden jaws). The larger vise has an offset center screw to allow vertical clamping without skewing.