To determine size for residential flags we generally start with the questions, does your flag have a sleeve at the top, or brass grommets? If it’s sleeved you need a 2.5x4, if it has brass grommets it’ll be a 3x5. For commercial accounts, if you’ve ordered with us in the past feel free to give us a call and we can look up your account and see what size you’ve ordered in the past.