There are two basic types of disposals, continuous feed or batch feed. Continuous feed is where the unit turns on with hitting a wall switch, which allows you to add more food waste continuously as it operates. The batch feed units, require that the stopper be inserted into the sink drain to activate the disposal. Batch feed units can still have the wall switch, but they will not operate without the drain stopper in it's on position. You cannot add more food waste while it's operating, thus you do a *batch* at a time.

Garbage disposals come in a variety of sizes. Commonly 1/2 to 1 horsepower. Some are available smaller than 1/2 hp, but 1/2 is a good place to start.

As you go more deluxe, the materials used in the grind chamber, shredder ring, and impellers change. PVC grind chambers become stainless steel. Impellers and shredder rings can be stainless steel or nickel plated.

Warrantees also increase as you go more deluxe. Some basic units will have 1 year parts and labor, while deluxe units can be 5 or 7 years parts and labor or even longer.

Some units are specifically designed for use with Septic systems, including a chemical catridge that will facilitate the break down of food waste in the system.

Whirlpool and Broan together manufacture all the 15 inch units. But they are available in a number of different brands. KitchenAid is one of the more popular brand names of the Whirlpool made units.

Dense pack is a feature that some models offer, which allows you to have the ram stay down and thus compact the trash more tightly in the bin. A few models also offer a activated charcoal air filter with a fan to help reduce odors. Virtually all models offer a removable key for safety.
Some models are built in units, where they must be installed under a countertop, and some are convertible where they can be free standing or built in.

There used to be 18 inch and 12 inch wide units, but they are no longer offered. The 18 inch size was discontinued many years ago, But the 12 inch size was only discontinued at in December of 2008. There used to be models with round baskets, but all the current units have rectangular bins.

There are some styling differences that may be of importance to you. Many models are available in white, black, bisque, or stainless steel.