Dodge is teaming up with Barrett-Jackson to auction off the final Viper and Dodge Challenger SRT Demon.

Set to be sold at the Barrett-Jackson Northeast auction in Connecticut this June, the models will be sold as a pair in what the company is calling “the ultimate last chance.” As FCA North America’s head of passenger car brands, Steve Beahm, explained “An avid collector could search a lifetime to try to put two vehicles of this pedigree together and never find it, it’s that elusive.”

The final Challenger SRT Demon has a Viper Red exterior and a custom Demon car cover. The model also has a single seat, a VIN instrument panel badge and the Demon Authentication package which includes build sheets and a Certicard. The winning bidder also receives a Demon Crate which includes front-runner drag wheels, a performance powertrain control module, a set of Demon-branded tools and a replacement switch module with a high-octane button.

Of course, the main feature is a supercharged 6.2-liter HEMI V8 engine that produces 840 hp (626 kW) and 770 lb-ft (1042 Nm) of torque. It is connected to an eight-speed automatic transmission which enables the model to accelerate from 0-60 mph in 2.3 seconds and run the quarter-mile in 9.65 seconds at 140 mph (225 mph).

The last Viper pays tribute to the first-generation Viper RT/10 as it has a Viper Red exterior with carbon fiber accents. The model also has black leather and Alcantara seats, a VIN instrument panel badge and an authentication kit.

An 8.4-liter V10 engine resides under the hood and produces 645 hp (481 kW) and 600 lb-ft (814 Nm) of torque. The engine is paired to a six-speed manual transmission which sends power to the rear-wheels via a limited-slip differential.

One hundred percent of the proceeds will go to the United Way and the models could bring in some pretty significant bids as the first Challenger SRT Hellcat sold for $1.65 million back in 2014.