Good luck with today's Brain Game riddle!

These parts of our bodies
Are both large and small
They have only five letters
But you double them all.

What are they?

Here's the SOLUTION.

SOLUTION:

INTESTINES.

The human body has a large intestine and a small intestine.

The word "INTESTINES" is 10 letters long. It's made of five unique letters: E, I, N, S and T, each of which occur twice in the word.