Sprint now offering $300 prepaid MC for each line you BYOD

While on chat for porting in BYOD Amazon deal, just after midnight, the BYOD page changed to include the $300 BYOD bunus.
Only terms so far posted: "Requires port and online registration; Prepaid Mastercard ships after 90 days."
Further terms:
Limit 5 per new account.
"You can register at www.sprint.com/offers, enter Promo Code 300BYOD313." Per Chat agent, when I inquired. . .
https://www.sprint.com/en/landing…:Shop:BYOD