This is a spare part designed for an old OSO brand hot water heater, 200 liter capacity. The original cover had several cracks to the degree it was disintegrating, and was no longer functional nor safe.
This cover will not fit the newer models painted in white, but may fit the older models painted in light blue.
There is no promise this item is suitable for anything, so beware that you will be using this entirely at your own risk. Behind this cover there may be exposed electrical terminals connected to the mains with potentially lethal voltages.