I think the sweeter heater is zero clearance as well double check the product description. It just means that it can be screwed straight to a wood wall and you don't have to have any concerns for fire risk or it can be right up against flammable bedding etc without fire risk (without MUCH fire risk atleast anything that runs on electricity has a little risk but these are known to be safe) because it's a radiant panel theres nothing that could spark or ignite like a heat bulb or space heater etc.
It also means the birds can literally sit on it if they wanted and not burn themselves, although my cozy coop panels on high feel pretty toasty to my touch atleast so I keep it on medium jsut in case they do press up directly against it.
This is how I have them set up. They look like little flat screens
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