Are you sure this has anything to do with Sonos?  It sounds like a CostCo initiative to me, as an incentive to buy Sonos from CostCo rather than from another retailer.  I may be wrong, but I doubt this is a ‘Sonos form’.

No doute 

Agreed, this is an offer from Costco, not from Sonos. It’s offered with the purchase of a Sonos, certainly, but the offer itself is not from Sonos. 

So you are suggesting that Sonos are offering a gift card that benefits Apple to incentivise customers not to buy Sonos direct from Sonos.  Forgive me if I continue to doubt that.

I may owe you an apology. It looks like it may be a collaborative offer between Sonos and Costco, presumably with a financial arrangement that allows both parties to benefit.

Thank you John.
Yes, you had founded the right words to describe the situation “Financial Agreement “