Pitch is the number of characters and spaces in one inch text, it's also sometimes referred to as (cpi). Your Selectric can either be 10-pitch (pica), 12-pitch (elite) pitch or sometimes both.
If you look at the front of your Selectric there is a ruler on the very lefthand side you'll either see a solid triangle which denotes 10-pitch type or a hollow triangle which represents 12-pitch type. You'll find the same labeling scheme used on the typing elements themselves.
The lever on each type ball is usually black. Only those with a specially character will have a white (or red in Europe) lever. This is to help distinguish between two type balls bearing the same type name but differing in this one respect.
On top of each type ball there is a triangle which points toward the platen whenever the typewriter is in lowercase position.