The 3" Hanger will hang guitars facing front ways but does not allow much room for the guitar to be rotated at an angle.
The 6" Hanger will hang guitars facing front ways and also allow most guitars to be partially rotated so they hang at an angle. It will not allow most guitars to hang completely sideways (perpendicular to the wall).
The 12" Hanger will hang guitars facing front ways and allow most guitars to be fully rotated so they hang sideways (perpendicular to the wall).
The above are general answers that apply for most guitars. But guitars come in many different shapes and sizes. To get an exact answer, you need to determine the widest part of your specific guitar. To do this, measure the distance from the center of the fret board to the widest part of your guitar. If you want to hang your guitar sideways and this distance is less than 6", then you can use our 6" Hanger and your guitar will be able to hang sideways, so it hangs perpendicular to the wall. If this distance is more than 6", then your guitar can be rotated to the point it almost touches the wall, but it won’t be hanging completely perpendicular to the wall. In this case, use the 12" Hanger so your guitar can hang perpendicular to the wall.