VALVE SEAT CUTTERS KIT 31 PCS. HIGH CARBON STEEL FOR VINTAGE. 21 + 8 + 1+ 1. CUTTER SIZES ARE AS UNDER. 45° ANGLE CUTTERS. 70 ° ANGLE CUTTERS. 1-1/4 – 7 0°. Guides – 7 mm, 8 mm, 8.5 mm, 9 mm, 10 mm, 5/16,11/32″, 3/8″. All Pilots Are Soft And Centered Both Ends. For Easy Reduction Of OD To The Requirements. This Item Is Manufactured From High Grade Carbon Steel. Each Cutter In Accurately Grade For Best Results, Optimum. For The Vintage Car Or Old Engine Cast Iron Head Restoration. THIS SET IS MADE FROM CARBON STEEL. Only to be used on Cast Iron or Alloy Seats. They will not cut Modern Hardened Seats. Feel Free To Ask Any Questions.