Parting Blade Tool Holder, uses 1/2 tall Parting Blades. Heavy Duty Boring Bar Holder, can use 2 size boring bars 3/8 and 1/2. Check out my other listings for more Atlas, Craftsman, Logan, Rockwell, Clausing and South Bend Lathe parts! Thank you for supporting my local small business - right here in Berrien Springs Michigan since 2004.