Christos Sykiotis, a rosin maker from Greece, has created an exclusive line of rosin to complement Arcus bows, while still greatly improving the sound of traditional bows. The three different grades can be mixed to balance the grip of the bow hair to meet your exact requirements. They make very little dust, and the sound is full and perfectly balanced. For best results, Arcus recommends using harder grades in cool weather, and lighter grades in warm weather.
The light rosin is most suited to violinists. As mentioned above, if the rosin is too hard during the winter months, it would be a good idea to switch to the medium. A cellist or bassist would use the dark, likewise swapping to the medium in the summer months. A viola player might suit any of the three grades, depending on their instrument and the temperature.