All the instruments are provided with the preamp which was designed and harmonized with respect to the used piezo pickup. Each piezo pickup is placed under a bridge. The violins have volume control. The pierzo pickup is powered by a 9V battery which is installed in the instrument and should last about half a year (depending on how frequently you play). The cellos body is made of high-quality hardwoods (I use mainly maple). The fingerboard and tailpiece is of ebony. The instrument is equipped by mini machine heads for precise tuning. Surface working is varnish. The price