Fishman Matrix Infinity Narrow PRO-MAN-MINF- new pickup system for acoustic guitars (under-bridge installation). Active Infinity preamp with switchable voicing to match guitar styles and sizes. Small sound control unit with volume and tone controls is installed inside the sound hole and enables an intuitive tone control. pickup width: 2.3mm, pickup lenght: 6.8 cm . Requires 9V battery (not included). Professional installation required.