The Kodak Ektacolor RA Developer/Replenisher Part B is an essential ingredient in darkroom photo development. It produces a 75 Gallons of solution that is usable up to 4 weeks. The solution is usable for the RA-4 process when developing photos in a tray, drum, or rotary tube. The developer has a built-in oxidation and evaporation protection for using roller transport and continuous processors. Liquid concentrates are provided along with the developer for easy mixing and handling.