Goodson Tools & Supplies expands its Hyper-Finish Diamond Valve Guide Sizing System to include six new mandrel sizes: 4mm 4.5mm, 5mm, 5.5mm, 6mm and 6.5mm (these are in addition to the original 7mm, 5/16”, 11/32” and 3/8” mandrels). Available in a Master Kit that includes four mandrel assemblies (7mm, 5/16”, 11/32” and 3/8”) that include both the mandrel and the abrasive, along with the drive head, honing oil and valve guide brushes.