When you need to reach into tight features or profile a complex part, you need to have a tool and tool holder with a narrow shape. The 35° diamond (rhombic) tool holders are offered in left and right hand configurations and in 3 shank sizes to fit most lathes. When you need to reach into tight features or profile a complex part, you need to have a tool and tool holder with a narrow shape. The 35° diamond (rhombic) tool holders are offered in left and right hand configurations and in 3 shank sizes to fit most lathes.