I had a house built and the builder did not install a garbage disposal or a switch in the wall. He did however put an outlet under the sink. So, I my plumber said he could install a garbage disposal but it had to be a batch feed type. 

Unlike a traditional continuous feed garbage disposal, you don’t have a switch to turn it on. You get a “cover” that acts like a key. You put the cover in the hole and turn it like a key to start the garbage disposal. While the garbage disposal is running the water does flow through the cover. The cover is a little large. 

The only thing I don’t like is that there is no option for installing a rubber collar. So, the hole is wide open and silverware can just fall in. I bought a Disposal Genie to help with this.