HTML 5 telephone number

HTML 5 telephone number validation:

<input type=‘tel’ pattern=“[0-9]{10,10}” class=“search” name=“number” autocomplete=“off” required>

can you please tell what does 10,10 mean here ? what is first 10 for and what is second 10 for here ?


{n,m} matches when the preceding character occurs at least n times but not more than m times.
In this case that makes the second 10 redundant.