Two sizes are available, both with 7/8" dia. steel single-lead Acme screws and double guide rods for smooth operation. The regular vise measures 7-1/4" x 14-3/4" and opens to 8"; the large vise is 10-1/4" x 21-3/4" and opens to 13" (maximum openings are less wooden jaw thickness).
The large vise has an offset screw to permit vertical clamping without skewing. Well made by a small European company, these enable you to incorporate a shop-made quick-release vise into a new bench or retrofit an existing one.