Legacy automotive brand Ford and Elon Musk’s Tesla have been all about partnering up lately, which is an unusual move for two businesses in direct competition.

After announcing that Ford would join Tesla’s Supercharger network in May 2023, Ford CEO Jim Farley announced on X on the morning of Feb. 29 that “eligible Mustang Mach-E and F-150 Lightning owners in the US or Canada can reserve a complimentary Fast Charging Adapter,” as well as now having access to the Tesla  (TSLA)  Supercharger network.

Related: Ford CEO responds to Elon Musk’s offer of electric-vehicle help

Ford  (F)  customers can reserve the free adapter, which is needed for the two specific vehicles to use the network, through June 30. After that, it will cost customers $230 to purchase one. Ford has said that by 2025, its vehicles will all feature the standard NACS plug.

Starting today, eligible Mustang Mach-E and F-150 Lightning owners in the US or Canada can reserve a complimentary Fast Charging Adapter for their @Ford EV and access @Tesla Superchargers by heading to https://t.co/PWyx4ynzXw pic.twitter.com/AKgU7XNQOB

— Jim Farley (@jimfarley98) February 29, 2024

I’ve tested it myself and it works great. Making something this easy to use takes a lot of hard work behind the scenes, so congrats to the @Ford and @Tesla teams for making this happen.

I would also like to thank @ElonMusk and the Tesla team for their close collaboration and… pic.twitter.com/0x9hlAD8Ps

— Jim Farley (@jimfarley98) February 29, 2024

Ford was the first automaker to forge the partnership with Tesla, followed by BMW, GM, Honda, VW, and many others.

While Ford has not clarified how many of the free adapters it currently has, Ford director of charging and energy services Ken Williams has said the product is “supply constrained” and Ford believes the initial demand will exceed supply. That means the free charger offer is very much first come, first serve. 

Ford EV owners can reserve their adapters by going to a special Ford landing page and logging in or enrolling in Ford’s BlueOval Charge Network. The adapter will begin shipping out to Ford customers in late March.

Ford’s moves challenge Tesla’s EV advantage

While the partnerships Musk has forged with automakers bring more money to Tesla, it also takes away the exclusivity of the Supercharger network. As Tesla continues to make price cuts to current models while promising new models are on the way, such as the Roadster, many investors have become skeptical about Tesla or lost faith in the EV maker entirely.

Related: Analyst reveals why Wall Street is skeptical about Elon Musk’s Tesla

Musk has been openly criticized for making multiple price cuts to Tesla models over the last few years, a move that investor Gary Black called “value destructive.” Black also addressed another issue causing anxiety on Wall Street in regards to how Tesla keeps financial information on its AI projects under wraps.

“The lack of financial disclosure in regards to Tesla’s AI projects made it impossible to forecast what to expect from the company in the future,” Black said in a tweet on Feb. 24.

Related: Here’s why the Tesla bears are starting to outnumber the bulls