Mirka HB-38 Handy. New, ergonomically designed sanding block with a handle, making it easier to finish flat surfaces.. Can easily be attached to the MV-912 Dust Extractor using a standard 20mm vacuum hose. With 55 holes on the face, dust is extracted quickly, providing a dust-free working environment. he Handy Block measures 3" x 9" (80 x 230 mm), for easy sanding large surface areas..