The Attachment number is criteria allow you to create rules that take actions on messages based on the number of attachments the message contains.
Select > to apply the rule to messages that are sent with more than the specified number of attachments.
Select <= to apply the rule to messages that have the same number or fewer than the specified number of attachments.
For example:
> 10 applies the rule to all messages that have more than 10 recipients.
<= 10 applies the rule to all messages that have 10 or fewer recipients.