Typical H-style harness. This is the one most commonly seen: www.amazon.com/Lupine-Cherry-Blossom-H-Style-Harness/dp/B0006N9FWU It fits around the ferret's neck(collar style), and around the upper rib cage directly behind the front legs. Good points- easy to find, adaptable fit for most sized ferrets, harder for average ferret to slip. Bad points- harder to fit larger/smaller ferrets most likely won't find these satisfactory. Particularly the tiny girls, as the harness may not adapt to a small enough size.
Ferrets: Contessa, Frankenfurter, Butterscotch. Kitties: Watson, Oskar DIP Sinnead, Vincent, Boris, Zeus and Athena, Willow, Mr. Frodo, Indie, Lucrezia, Judge, Odin, Miss Emily, Suki, Cody, Aristotle. RIP Herne, Ligeia, and Mr. Stubbs