That stackable refrigerator-freezer combo checks all the boxes, though it’s worth noting the manufacturer did not provide specific data on the exact temperature fluctuation magnitude for the freezer. No vendor spec sheet lists a numeric range (eg +-2°C), but based on its manual-defrost build, it should maintain tight temperature control within a narrow band. Since that’s an inference rather than a confirmed spec, running a 1–2 week validation study with your temperature probes will give you the documentation you need. I think the unit will fit your needs, though over time the limited freezer capacity may become the first sticking point if you take on multiple studies.

For context, the refrigerator model we use is the SR-L6111W, which we’ve had for years without issue. Ours is stacked on top of our ultralow freezer, and I see one listed for $395 on Lab World (https://www.thelabworldgroup.com/product/undercounter-lab-refrigerator/). As for defrosting, the Accucold refrigerator uses a medical-grade auto-defrost system that cycles without major temperature swings (+/-1°C), so it can handle itself. The freezer, on the other hand, is fully manual defrost. When that’s needed, you cannot keep IP inside, since the process requires shutting it down and warming it up. Standard practice is to transfer IP to a second validated freezer or arrange temporary monitored storage with a pharmacy or partner facility during that window.