the revolutionary new pac food core temperature valve allows accurate temperature reading of your food by allowing the probe thermometer to be inserted into the centre of the food, while in the bag. the valve does not compromise the seal of the bag, but does allow temperatures to be read accurately. folding of the bag or using an infrared gauge will only measure the surface temperature the centre of the product will be most probably be at a marked difference source httpwww.pacfood.com.auibtcv.php