Deleting files with SIZE range

The -a in an explicit AND operator that allows you to join two primaries. In this case creating a range using -size.

rm -rf `find . -size +300c -a -size -400c`;

The above command deletes the files which size are in between 300kb to 400kb.

Note the size is a numeric argument that can optionally be appended with + and -. 

Numeric arguments can be specified as

   +n     for greater than n,

   -n     for less than n,

    n     for exactly n.