The Attachment size is criteria allows you to create rules that take actions on messages based on the size of any attachments to the message.
Select > to apply the rule to attachments that are larger than the specified size.
Select <= to apply the rule to attachments that are smaller than or equal to the specified size.
For example, <= 10 MB applies the rule to all messages that are equal to or smaller than 10 megabytes.
The Attachment size is criteria is applied to the total size of each attachment.