To match certain specific characters or ranges of characters use . You can separate the different characters that you want to match inside the brackets with commas; this is not mandatory (some systems do moan if you don’t use commas on complex expressions) but it does make the pattern more readable.
To specify a range of characters use the dash (-). This specifies a set or range where the range starts on the left-hand side of the dash and finishes on the right-hand side of the dash.
You should always use the  when you want to home in on a string match. Suppose we wanted to match any single number, we could use:
However, there is an easier method by using the dash (-):
or any lower ...