25.4 mm 25.4-24tpi Quill Adjustable deg Bicycle Stems
Bar clamp diameter is the diamater of the handlebar.
S.H.I.S clamp diameter is the steerer tube diameter.
Stem angles are measured perpendicular to the clamp. For example, a 90 degree stem is straight. Sometimes, this may also be refered to as a 0 degree stem. If two measurements are listed, the stem can be flipped for angling up or down.