That is the kind that I DIDN'T want, since both my freezers are always full. The main problem with these units is that you must put the bowl in the freezer each time that you make ice cream! So say you want to make at least a gallon of the stuff. Most make up to about a quart per batch. You'd have to pre-freeze the bowl at least about 4x separately!! Too time-consuming for me!!
Also, most or all of the self-contained units have their own built-in sealed refrigerating system that freezes the mixture for you as it is churning and beating air into the ice cream! I once made Strawberry Sorbet with it. Came out light, airy & very good!!