Microwave ovens can emit microwave energy that may interfere with nearby electronics, particularly those operating on the 2.4 GHz frequency, such as 802.11 wireless cards and cordless phones. Leakage levels vary based on the quality of the oven's shielding, especially around the door, and running the oven empty can increase this leakage. While small amounts of leakage are generally not harmful to humans, sensitive electronics may be affected. Most microwave ovens include warnings in their user manuals against operating without a load, as this could lead to overheating of the magnetron and potentially higher emissions. Users are advised to consult their oven's manual for specific guidance.