An F-attachment extends the trombone's low range with additional tubing that drops the pitch a perfect fourth. When the trombonist presses a trigger, a rotary valve redirects airflow from the standard tubing into the F-attachment's tubes.   The F-attachment was patented in 1839 by German instrument maker Christian Friedrich Sattler. It allowed the newly popular tenor trombones to play many parts originally written for larger bass trombones. Today B♭/F trombones are the standard in most orchestras.  While the F-attachment gives trombonists access to lower notes and more possibilities with trills, it also makes the instrument considerably heavier. Notes with the valve engaged require more air and can sound stuffy or weak without extensive practice and top technique. Some soloists favor the cleaner sound of the straight slide B♭trombone.