The K4 Wilson Pickup has since 1985 been the professional choice of amplification system on the market for amplifying acoustic string instruments. The K4 pickup for 4-stringed double basses and other low frequency instruments (bass balalaika etc.) has all the assets you need when playing on a stage or by recording in a studio. The natural wood sound is focused and gives the punch that the bass has as well as the body and warmth. It is clean and clear and the sound is great for pizzicato and arco playing without absolutely no feed back at any levels. The Wilson K-Pickup amplifies each individual string on your double bass covering the frequency range from below the low B/C-string up through the harmonics overtones and further beyond the audible capacities of the human ear. Testimonials from famous bass players worldwide proofs the outstanding high qulity of the sound you will get from your double bass amplified with a Wilson Pickup System. By simply rotating a Pickup slightly you can adjust the volume level of each string individually – making the perfect balance between the output from your strings. A feature not covered by any other competitor. 4 pickups are gathered to a Switchcraft 121 extension jack. Special mounting tools and mounting bracket are included with each set of K4 pickups.