Its because you use "an" if the next word 'sound' like a vowel, so it's an LEO.
I do not get upset when someone makes a grammar mistake, but I could not resist pointing out your improper use of the word "Its". Your use of "Its" is really a contraction for "It is", and apostrophes are used with contractions. You should have used the contraction "It's".
Its and It's - Glossary of Usage - Commonly Confused Words - Its versus It's