The supermodel and executive producer Michael Rucker discuss their homecomings to the series, the dynamic cast and why Christian Siriano remained as the designer’s mentor with the network shift.

Klum and her former co-host Gunn, 71, both exited “Project Runway” seven years ago, with the Sports Illustrated Swimsuit cover star sharing a heartfelt goodbye at the time.

Season 21 of the fashion design competition is set to premiere on Thursday, July 31. It will see the return of Heidi Klum as host, alongside Nina Garcia and Law Roach as judges and Christian Siriano as mentor. The show, which has aired on both Bravo and Lifetime, is moving to Freeform this season.