This Avantco 19386447 stainless steel shelf step is a direct replacement for what came with your Avantco air curtain merchandiser. Use it to replace a worn or missing part to keep your unit operating efficiently. It can also be used to keep an extra on hand. This step allows your unit to showcase your product better. It's compatible with Avantco HAC-51-W and HAC-51-B air curtain merchandisers.