9 pin miniature preamp tube (Amplification Factor = 60),</br>Less gain than a 12AX7</br>Preferred by Blues and Jazz Guitarists alike.</br></br>Product Description</br></br>9 pin miniature preamp tube (Amplification Factor = 60), Less gain than a 12AX7, Preferred by Blues and Jazz Guitarists alike.</br><br/>http://www.amazon.com/gp/product/B000UMFQHA