The Model 400 Heavy-Duty Base is designed for projects that require added holding power. Recent engineering improvements allow for the Model 400 Heavy-Duty Base to support weight up to 75lb at 45 degrees. Recommended to be used with the Model 437 Heavy-Duty Fixturing Head. This base accepts any 1" diameter shaft to a depth of 1.7". The single knob controls the Head's movement through 3-planes (90 deg. Tilt, 360 deg. Turn and 360 deg. Rotation. This square base is 4.125" x 4.125" and has four 0.3125" mounting holes (mounting screws not included). A hole is provided in the bottom of the base for a 1/4-20 flat-head screw to permanently attach to any shaft.