at1010,
I don't, but tried a couple different ones and didn't like them...especially in low light conditions.
I'm a right handed shooter. When I come to full draw, I line up the string with the left side of the sight pin guard. I use a kisser button (right corner of my mouth) and sight (look) on the right side of the string with the string on the end of my nose.
As I'm lining up a sight pin, the string gets lined up with the left side of my sight pin guard. This method maintains my lefts and rights. Right before I shoot, I make a mental note to check my string with the sight pin guard (lefts & rights) and release. I've been doing this for over 35 years and can consistantly shoot 4" groups at 50 yards.
Bowhunter57