A bit holder that includes a front portion and a shank axially depending from the front portion. The front portion having an axial length that is less than the axial length of the shank. A combination bit holder and base block that includes the bit holder with the front portion having an axial length that is less than the axial length of the shank. The base block including a mounting portion and a device receiving portion, the device receiving portion including a length that is the same or less than a length of the mounting portion. The base block having a device receiving portion that includes a length shorter than a length of the mounting portion adapted to provide increased access to the rear of the bit assembly allowing the base blocks to be mounted closer to each other for micro-milling operations. Shortened bit holder shanks are reconfigured from prior art to provide increased holding power between the bit holder shank and base block bore.