96 Mazda Protege fuses

Does anyone know what fuse to put in slot 29 on the interior fuse box? The owners manual has the description as ‘heater’ and the protected component is ‘heater, air conditioner’. It is supposed to be a 40 amp fuse but all the fuses I found at an auto parts store are the wrong shape. They don’t have anything listed in their computer system as to what replacement to use. I normally would just look at what’s in there but the slot is empty and the owners manual does not say what to replacement parts to use for anything.