Simplify the following text for a Grade 7 native English-speaking person.
Original: Modern returning boomerangs can be of various shapes or sizes as can be seen in the diagram of modern Boomerangs to the right of page .
Simplified: However , some boomerangs do not return because their wings do not have the right profile . Most of the boomerangs are made for right-handed use , left-handed people have to use other boomerangs that are mirror-inverted or have to throw with their right hand .