<p>A window vent for mounting in a window frame (10) to allow communication between the inside and the outside of the window has two parts (16, 18) which can be pushed into a slot (20) through the window frame, from opposite sides of the frame. The two parts then form an enclosed passage through the window frame through which air can circulate, and no tools or other fixings are needed to retain the vent in place in the slot.</p>
