Lauren Guitar pitch pipe. One reed for each string. Reed is blown to produce the note, and then the player tunes the string to match the pitch. Plastic housing with brass reeds.
Electronic pitch pipe for violin and mandolin. This produces tones to match each of the strings on the violin. This will not tell you if the strings pitch is high or low. It only produces the tone that you then match by ear.
This works with all Acoustic, Electric and Bass Guitars, alond with many other instruments such as mandolin and fiddle. It automatically adjusts to the string you are tuning, and tells you if it's too high or too low.