Extract the sequence of retrotransposons sites

Question

[elisheva]

Hello
I am trying to locate the AT-rich sites of retrotransposons.
I downloaded the repeats table from the genome browser with all transposable elements (hg38, RepeatMasker track).
I thought to filter the file to extract only SINE and LINE coordinates. However, I have no idea how many bases should I extend the intervals in order to get the AT-rich sites.

Does anybody have any knowledge of this subject?

Thanks