King 3B F Attachment Trombone. King 3B standard model professional F attachment Trombone is a solid well made Trombone by a well know instrument company with a long history of quality instruments. The trombone has been cleaned, had all major dents removed, all tuning slides move freely, and the main slide is clean, fast, and quiet. The instrument comes with the original King Trombone case. A mouth piece can be added for an extra price.