Microsoft has been running a BOGO deal offering up a free Lumia 950 with the purchase of a Lumia 950 XL. It's a pretty good deal, and apparently it's also fairly popular (or Microsoft's inventory was low to begin with). According to reports (via Windows Central), the deal will be ending on April 29 (that's today).
In case you're wondering, here are the Microsoft Store's Ts&Cs for the deal:
Offer valid from April 25, 2016 to May 1, 2016. Offer is available while supplies last. Available in Microsoft retail and online store in the United States (including Puerto Rico) and Canada only. Offer valid with purchase of unlocked 950XL in either color.
The bottom line is, if you want to get in on this deal, then you'll want to act fast. That "while supplies last" caveat seems to be in play here, and so get out that credit card and get your order in before it's too late.