Dominant PRO violinstring E Steel string, tin plated. According to the manufacturer":

• exceptionally powerful
• good balance of brilliance and warmth
• broad range of sound colors
• supports the radiance of the instrument in the long term
• reacts immediately with a focused sound core 
• a sound that fills the room
• bell-like tonal character 
• high resistance to bow pressure
• suitable for soloists 
• very high level of dynamics (can be played very quietly and very loudly)

Removable ball: can be used on fine tuners for loop as well!