The:
• [0-9]{1,2} is any 1-2 digit number
• : is simply the colon used in your time format
• ( & ) tell Word to store whatever's between them
• \1 says to used the first stored value (i.e. what was between the ( & )) for the replacement.
For more on wildcards, see: https://wordmvp.com/FAQs/General/UsingWildcards.htm

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]