the red wilton that has the steel slider that fits in the dynamic jaw is called a "bent vise",, a flat steel plate is bent into a U shape and placed into a mold,,, molten cast iron is poured into mold,,,looks like the wilton trailer hitch is made the same way,,,i have a unmarked 5 inch bent vise,where the bent part is all cast iron,,the bulldog prentiss dynamic jaw is cast in one piece and the square slider part is machined,,,vises that have flat smooth jaws are Machinist Vises,,so no damage to the part,,the cheapest vises that have the lead screw exposed above the "slider" are called bar vises, they used to take a steel bar,place it into mold and pour in the molten cast iron,,most made now make the entire dynamic jaw out of one cast piece..