Some operations also have installed components in mechanically ventilated gestation and breeding facilities called cool cells. Cool cells can be effective in keeping room temperatures 10 to 15 degrees cooler than outside temperatures by pulling the fresh air through wetted corrugated material. Another effective method to cool sows during lactation is the installation of nose coolers. In farrowing rooms that use negative pressure systems with a plenum as the air inlet source, a tube can be connected to the plenum and directed to the bottom of the farrowing crate near the sow's nose while she is lying down. This supplies constant air movement across her face when the ventilation system is activated.