Collect shirt size for donor incentive

Open Online Giving → Campaigns or Online Giving → Forms, select the campaign or form, then go to Giving Experience → Form Builder and select the appropriate Pre-Payment Form or Post-Payment Form.

Add a clearly labeled custom dropdown for T-shirt size with the offered sizes and an appropriate Not claiming a shirt option, keeping it before payment if fulfillment details must appear in the first notification. Explain that it applies to donors choosing the shirt incentive; do not assume a size question changes incentive eligibility or inventory. Include the response and selected incentive in the fulfillment export and test qualifying/nonqualifying donors.