Reading the code700XH300 is a 70.0″ pitch length belt (the first number is the length in tenths of an inch), XH pitch, 3″ wide. The last three digits are the width in hundredths of an inch. Common widths are 200 (2″), 300 (3″) and 400 (4″).
Counting teethPitch length divided by the pitch gives the tooth count. A 70.0″ XH belt has 80 teeth. If the code has worn off, counting the teeth is the most reliable way to get the length.
XH or 14M?XH is a heavy-duty imperial section. A 14M HTD belt is the modern metric equivalent for new drives, but the two need their own pulleys, so stick with XH on an existing drive.