Buildings with brick cavity walls require open joints to ventilate the cavity. Wasps, drones and mice love these openings to gain access. Bee-biters will allow ventilation but effectively block all vermin.
Bee-bitersĀ® biters are the only available wheephole covers that can be placed in existing walls, that adjust automatically to any joint width and lock themselves. And best of all: they are off stainless steel!