Dodge will auction off the last production Viper ever built together with the last Challenger SRT Demon and donate all of the proceeds of the sale to the United Way, the automaker announced mid-April.

The “Ultimate Last Chance” duo – both painted in Viper Red with Alcantara black interiors in tribute to the first Dodge Viper RT/10 – will cross the block at Barrett-Jackson’s Northeast auction in Connecticut on June 20.

Putting out a combined 1,485 horsepower, the vehicles come with special badging and authentication documents. The Viper is the last to have rolled off the line at Chrysler’s now-closed Conner Avenue assembly plant in fall 2017.

The auction house has not offered a pre-sale estimate on the pair, but in 2014 the first 707-horsepower Hellcat built netted US$1.65 million at auction, and both of these cars are much more exclusive than that one’s turned out to be.