Unlike other brass instruments, trombones are . . . well, simple (to shop for, not necessarily to play). Still, buying any instrument for the first time can be a horrifying experience, so most parents/musicians find themselves in a bit of trouble when trying to find their first trombone. There are a few things to work out and learn about, but once that's taken care of, shopping for a trombone can not only be an easier experience, but it can be a bit of fun too!
Types of Trombones
There are three members of the trombone family type tenor and the bass trombone.
What to look for
It's important to keep the level that you or the person you're buying for is playing at. Buying your 9 year old son an expensive professional trombone won't make his playing any better, and it could turn out to be a huge loss if he decides that it's not for him. Trombone manufacturers produce instruments based on standard classifications Trombones'>professional. These generally reflect the quality of the instrument you are getting, but do not necessarily define which features you will or will not get at a certain level. Rather, the classifications are for general reference.
One term you'll have to get acquainted with is "'''bore'''," which is the inner diameter of the inner valve, not a description of the entertainment value of the instrument. These measurements are expressed in thousanths of an inch, with 481" being a student appropriate size, and 547' being appropriate for professionals. Smaller bores produce more resistance, which is ideal for students. More resistance makes it easier for the player to hold a tone.