Graflok and spring (also called Graphic) backs are very very different. Thinking they're the same will get you into trouble.
Originally Posted by Dr Croubie
The Graflok back's focusing panel is removable; that's what those levers with springs and a hook at the end are for. The focusing panel also lifts up to allow insertion of sheet film holders and insertion type roll holders. The focusing panel is removed to attach a Graflok accessory such as a roll holder (not insertion type).
The spring back's focusing panel is permanently attached to the back, lifts up to allow insertion of sheet film holders and (yes!) insertion type roll holders. The most common insertion type holders for 2x3 cameras are Adapt-A-Roll 620s. There's also a mythical Busch roll holder. The most common insertion type roll holders for 4x5 cameras are probably Cambo/Calumet, Sinar and Toyo.
Visit www.graflex.org, where the differences between Graflok and Graphic (also called spring) backs are explained more fully and to learn more about AAR 620s.