Application For Mixing Drywall Mud or Paint. Paint Mixing Paddle, Shaft Dia. 5/16 in, Length 19 3/4 in, Head Dia. 1 3/4 in, Spiral Head Type, Max. RPM 900 RPM, Steel, For Mixing Drywall Mud or Paint, For Use With 3/8 in or Larger Variable Speed Drill.