-Compressor Location and Clearance
You'll also want to pay attention to where the compressor's intake and exhaust are located. Depending on the layout of the area where you wish to place the cabinet, you might need to make some adjustments.

If the exhaust is located on the right side of the unit, you won't be able to place it flush up against a wall or cabinet on its right side, for example.
Some models offer a "front breathing" design, which means that the intake and exhaust are both located on the front of the cabinet, which helps to lessen the side-to-side clearance requirements.
When in doubt, it's always a good idea to look at the Specification Sheet for any installation requirements and clearance. Many manufacturers won't honor the warranty if the unit is found to be installed improperly.

-Doors and Drawers
Undercounter refrigerators and freezers are available with both doors and drawers. When you start looking at multi-section models, you often have the option of mixing and matching door and drawer sections.

-Drawer sections will have less overall storage space compared to a section with a door, but may be more convenient since you can load food pans directly into the drawers. It all depends on what is most convenient to you in your situation.

-Glass doors give you the benefit of being able to see what's inside without opening the door. They also allow for a bit of a merchandising effect for front-of-the-house situations. A trade-off is that you'll lose a bit of energy efficiency since a solid door is better insulated.

-Work Top Refrigerators and Freezers

Work top refrigerators and freezers function in the same manner as their undercounter cousins, but have a handy backsplash attached to the back to protect the wall from food particles and splashes. Their top height (minus the backsplash) is the same as undercounter models too, providing a convenient space for cutting vegetables and fruits, preparing portions of ingredients, and more.

Some manufacturers' models have a backsplash that's bolted or attached to the top of the cabinet, while some others boast a seamless, one-piece construction. The latter is much easier to clean and sanitize, since food particles can't get trapped underneath the seam.

-Chef Bases

Refrigerated chef bases are gaining popularity because they bring close-at-hand refrigerated drawers right to the cooking line. Boasting a rugged top, they're designed to hold countertop fryers, griddles, charbroilers, and more on top, while housing the food you're waiting to prepare right underneath. A few freezer chef bases are available as well. Sizes range from 36" up to 120" wide.

-Purchasing Considerations

Since these units exhaust warm air like all refrigerators, be sure to account for this when calculating the CFM (cubic feet per minute) ventilation requirements for the exhaust hood over your cooking equipment. You'll want to make sure that you have enough airflow for safe and efficient operation of both the cooking equipment and the chef base's condenser.
Most manufacturers offer a "Marine Edge" top on their chef bases that helps contain drips and spills. This is a nice feature, but will reduce the overall usable dimensions of the top fractionally. You will need to look carefully at the Specification Sheets of both the chef base and also the equipment you plan on placing on top to make sure that the legs will still sit correctly on the top. If not, you might need to specify a flat top chef base.
Check the Specification Sheets of the chef base as well as the equipment you plan on putting on top of it to make sure you don't exceed the weight limit of the base.
Often, the cooking equipment needs to be mounted on legs to provide a specified minimum amount of clearance between the bottom of the equipment and top of the chef base. Some manufacturers even recommend the use of a heat shield on top of the chef base to deflect some of the heat from the cooking equipment away from the refrigerated cavity of the chef base. It's important to follow the manufacturer's guidelines to maintain food safe holding temperatures and prolong the unit's life.

Reach In Refrigeration

-Undercounter Refrigerators and Freezers
These models share the same basic cabinet construction, with the main difference being the thermostat and refrigeration system. Undercounter models are available in sizes as small as 24" wide and as large as 119". Even though undercounter refrigerators and undercounter freezers look similar to worktop units, which are discussed later, they aren't best for use as a work space or for holding countertop equipment. A few manufacturers offer dual-temperature undercounter units, which have both a refrigerated compartment and a freezer compartment for even greater versatility.

-Height
When it comes to the height of the undercounter unit you're looking at, it's important to understand what the lingo means, read the Specification Sheets carefully, and break out your tape measure! A typical undercounter unit sits approximately 36" tall, including the casters or legs. Most manufacturers offer a "Low Profile" and "ADA Height" version of their cabinets as well. This is where you'll need to pay attention.

For example, True Refrigeration's "ADA Height" models are 34" high, which would sit level with a typical ADA-height (Americans with Disabilities Act) countertop.
If you want to have your undercounter unit fit under an ADA-height counter, you'll need to purchase the "Low Profile" version which sits just 32" high.