Left hand quick spiral reamers designed for machining through holes in steels with tensile strength up to 700 N/mm2, long-chipping aluminium, copper and soft plastics. Due to the long taper lead they are not suitable for blind holes. The reamers have reduced number of flutes. When operated at the same cutting conditions in comparison with conventionally used, multi fluted reaming tools, and used with up to 100% higher reamimg allowance they produce a clean, chatter-free surface quality, an excellent concentricity on the bore and also gain a substantially longer tool life.