I believe I purchased this off of Steve Summitek back when he was still in business. I also bought my fantastic print washer from him as well. This slosher is very well built, just like his print washers were, and will last a lifetime. Holds 6 sheets of 4x5 film for development in an 11x14 tray. Works much better than hangers and tanks. I've since stopped shooting large format and am selling all my stuff off.
You put the film in emulsion up into the dry slosher. Fill the tray with developer. I used 1500-2000ml. Set the slosher into the tray, push it down to the bottom then simply agitate the tray very lightly on the corners for the first minute then each corner every minute. That was my routine. I got very even development. It doesn't take much agitation at all. The film doesn't float, it will stay under the developer. You can see it and practice with some old useless negatives and some water.