I currently use the X3 models for my 4- strings violin and the E4 for my 5-string violin. Both are very light, easy to use and offer very good sound projection. The E4 has surprised me because it is not easy to find a bow with a good balance when you play a 5 string violin, especially when you use very different types of strings (C and E). This bow it is strong and very light, very good when you have long gigs and play outside! My Arcus bows are really essential on my tours.