Yamaha YSL-447G Intermediate Trombone YSL-447G Intermediate Trombone The Yamaha YSL-447G Trombone offers the best in options for students looking for a quality intermediate instrument With an 8-1/2-inch gold brass seamless bell and one-piece drawn brass outer handslide, the YSL-447G has the bore and body designs to meet the needs of the player The Yamaha YSL-447G Trombone offers the best in options for students looking for a quality intermediate instrument With an 8-1/2-inch gold brass seamless bell and one-piece drawn brass outer handslide, the YSL-447G has the bore and body designs to meet the needs of the player