Jack Screw Set, Height (In.) 3-3/4, Dia. (In.) 1, Application Leveling Work And General Tool Room Use, Includes 6 Pieces: 20-Pitch Jack Screw 1-1/2 to 2-1/4 in Range, Extension Base 1/2 in and 1 in , Auxiliary Pointed Screw, Extension Base for Non-Flat Surface, Extension V Base for Cylindrical Forms