Photos via @StringCheeseIncident on FB

After taking a Saturday-night time warp back to the ’90s, The String Cheese Incident celebrated their single-set Sunday show at Hulaween with a special appearance by bluegrass maven Billy Strings and his bandmates Jarrod Walker and Billy Failing.

This sit-in marks the second time Strings has joined SCI this year, previously offering a killer take on “Black Clouds” and several other cuts at this year’s DelFest.

“Billy Strings is somebody that I’ve met in the bluegrass world. I played with the Travelin’ McCourys for a little while as a side project, and ran into Billy Strings a lot,” SCI’s Bill Nershi recently told “…He’s really on fire, that kid. He’s really, really amazing, his singing and playing.”

At Hulaween, SCI invited Strings, Walker and Failing out for the first half of the set, starting with the bluegrass classic “Remington Ride.”

The Bill Monroe original “The Walls of Time” followed, before Deadheads were thrilled to hear “I Know You Rider.” The Strings & Co. sit in was then rounded out by a take on SCI’s “Rivertrance.”

“Thank you @sci_official for having us sit-in!! Love y’all ❤️” Strings wrote afterwards via Instagram.

Other highlights from SCI’s closing Hulaween set included a “Best Feeling”> “Exodus”> “Best Feeling” jam and a rocking “Colorado Bluebird Sky” closer.

For more information on Hulaween visit the event’s official website.