Faithfull FAIPRSB32 Piercing Saw Blades 130mm (5in) 32tpi (Pack of 12). Teeth 32 tpi. Pack of 12. The Faithfull Piercing Saw Blades have been designed for cutting thin sheet metal such as steel, copper, brass and aluminium. Spare blades for FAIPRS.1 x Pack of 12 Faithfull Piercing Saw Blades 130mm (5in) 32tpi. The Faithfull Piercing Saw Blades have been designed for cutting thin sheet metal such as steel, copper, brass and aluminium. Spare blades for FAIPRS.