WHO: What began in 1969 as a low-key side project for Jefferson Airplane members Jorma Kaukonen (guitar/vocals) and Jack Casady (bass) turned into a lifelong pursuit—a band active for parts or all of every decade since. Although more than two dozen other musicians have weaved in and out of Hot Tuna’s recording and touring lineups, the 77-year-old Kaukonen and 74-year-old Casady—who met way back in high school—have been the only constants. They’re joined in the latest configuration by drummer Justin Guip, whose résumé includes an eight-year run working with the late Levon Helm.

BONUS MEMBER: Guitarist Steve Kimock, a longtime Bay Area favorite who has participated in such Grateful Dead-related projects as Kingfish, Phil Lesh and Friends, The Other Ones and the Rhythm Devils, will join in for the vast majority of Tuna’s two Brooklyn Bowl sets (according to the band’s publicist), which should significantly augment the group’s already potent improvisational firepower.

SOUND: Blues- and folk-based rock influenced by early-American musicians like Reverend Gary Davis and Lightnin’ Hopkins, at times run through a psychedelic filter that can extend songs well beyond their recorded lengths in concert.

SPIN: Some of the best Tuna releases have been of the acoustic variety (1970’s self-titled debut, 1971’s First Pull Up, Then Pull Down), but Friday’s show will be an electric affair, and there are fine catalog entries in that realm, too. Start with 1972’s Burgers, generally acclaimed as the band’s best studio record, which bridges the acoustic and electric approaches, then try 1975’s America’s Choice, first of the so-called “Rampage” trilogy (1975’s Yellow Fever and 1976’s Hoppkorv are the others), which found Hot Tuna embracing a heavier, electric guitar-forward style. In terms of individual songs, the instrumental “Sunny Day Strut” and the dark, slinky “Serpent of Dreams” should knock over those on the fence about buying tickets.

HOT TUNA with Steve Kimock. September 7, 8 p.m., $35-$93. Brooklyn Bowl, 702-862-2695.