To take advantage of the offer, just mention it while ordering.
Arby's Classic Roast Beef features thin-sliced roast beef on a toasted sesame seed bun.
If you liked last week's two for $6 Drive Thru Deal, it looks like they're keeping it on as a limited-time special (they're calling it a "Everyday Value"). For $6, you can get any two of the following: Buttermilk Crispy Chicken Sandwich (they were just calling it the "Crispy Chicken" last week though), Crispy Fish, and Beef 'N Cheddar.
Arby's Drive Thru Deals are slated to change each week and they plan on offering them for as long as dining rooms stay closed.
Photo via Arby's.