Product review (5 stars): it fits my GE refrigerator 18.2cu-ft
I purchased this wire shelf from an eBay seller. I got it used for 28 bucks including shipping.

It fits my GE refrigerator; the frig size is 18.2 cubic feet and the frig model is GTS18XCSARWW. From top to bottom, the inside of my freezer compartment measures about 16.25 inches. From side to side, it measures about 24 inches.

After the shelf is installed, the right half is about 3.25 inches from the top of the freezer (enough space for 2 ice cube trays). The left side is about 6.25 inches from the top.

It has a durable plastic coating. It is easy to install.

I also have a small wire shelf that I bought at a local store. It sits on the bottom of the freezer.  Both of these shelves make it easier to stack food in the freezer.