Abou the D'Addario PW-CT-30 Nexxus 360 USB Rechargeable Tuner for Violin:
 
The Nexxus 360™ Rechargeable Violin Tuner offers the fastest, most accurate tuning for violinists. It features an extra bright, full-color LED with 360-degree adjustability for the perfect viewing angle, and screen clarity in any lighting. Whether you're in the classroom or on the stage, you can enjoy up to 24 hours of tuning, and an auto power-off setting to help you maximize each charge. The Nexxus 360's piezo reads vibrations and is optimized for orchestral stringed instruments. Plus, it offers our widest hertz range—from 415 to 465Hz. For the best accuracy on your violin, attach the tuner to any part of the shoulder with the non-marring clamp. 1 ft USB-C cable included.