This does not include a USB-C power adapter.
The MagSafe Charger on its own can charge an iPhone 12 at up to 15W with Apple's 20W USB-C charger, but if you use that same 20W USB-C charger with the MagSafe Duo, an iPhone 12 will be limited to a maximum of 11W. You can use a 27W+ charger instead and it will charge at up to 14W, but it is not able to hit that 15W maximum.
How many are you buying?
NOTE: A few commenters have mentioned that they haven't received orders for other items weeks after placing the order from this store.
for $189 you'd think they'd throw in a charger adapter…