A rotor pair for a compressor block of a screw machine includes a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis. The number of teeth of the main rotor is 3 and the number of teeth of the secondary rotor is 4. The relative profile depth of the secondary rotor is at least 0.5 rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor. The ratio of the axis distance of the first axis from the second axis and the addendum circle radius rk1 is at least 1.636.