Microsoft has launched a new promotion in an effort to entice owners of Apple's MacBook Air to switch to the new Surface Pro 3. The company will offer up to $650 in credit toward the purchase of the tablet in exchange for a working MacBook Air.

Microsoft has been marketing the Surface Pro 3 as a replacement for both a laptop and a tablet. The device is larger than many other tablets, and owners can purchase a removable keyboard for an additional $130. The tablet has a stand that enables it to sit on a flat surface and be used like a laptop with the connected keyboard. The Surface Pro 3 starts at $799, meaning that MacBook Air owners could purchase the tablet for as little as $150.

Microsoft has touted a number of advantages of the Surface Pro 3 compared to a MacBook Air. The tablet is lighter at 1.76 pounds, and includes a pen for writing and drawing. As it runs Windows, users also have access to Microsoft Office and other common programs. Microsoft may have difficulty convincing many MacBook Air owners to switch to a Windows machine, but that won't stop it from trying.

"Refined to its essential elements, Surface Pro 3 is as beautiful as it is functional so you can stay productive from anywhere," says Microsoft in a statement. "Just slip it into your bag or backpack and go."

Microsoft would not discuss the trade-in value of specific models of the MacBook Air, insisting that it could not provide an estimate unless the physical device was brought into a Microsoft store for inspection. While $650 is the maximum amount, most MacBook Air owners will find their devices appraised at much less than that. The technology buyback company Gazelle prices a new, fully upgraded MacBook Air at $628, just below Microsoft's maximum. However, the stock model without upgrades is valued at only $413.

The offer opened on Friday and will continue through July 31 or "while supplies last." Microsoft also ran a similar campaign in 2013, offering to buy used iPads for $200 in credit toward the purchase of a Surface tablet.