This is where I saw it and she never says what they are used for.

How long is a long arm quilter? Thanks

she has videos that shows how she uses them

Most people consider anything larger than 18" throat a Long Arm probably because you have to have long arms to use one that big--LOL JK!

8-11" or 12" is short arm.

12-18" is mid arm but there are some 18" machines that I would consider a long arm because of all the bells and whistles and how expensive they are. These may or may not have a foot controller. Some are based on commercial single purpose machines and others are stretched domestic machines.

Longarms have a single purpose, usually come with the frame and do NOT have a foot controller. Now they make some machines that blur the line between Long Arms & Mid-Arms. They do have a foot controller but sit inside of a table like commercial sewing machines only they turn them a different direction--HandiQuilter pops into my mind with their Quilt Table Fusion & Avante machines, APQS George, and Gammill has a home table now.