valtstool vertikaaltasandil üksteise kohal asetseva kolme mittereverseeritava valtsiga (vt valtstool; vrd duo-valtstool, kvarto-valtstool, paljuvalts-valtstool), a type of rolling mill stand consisting of three working rolls contained in a single housing (see: stand; compare: two-high stand, four-high stand, multiroll stand)