Feature: Effective: This ultrasonic repellent is effective in indoor spaces. For good results, a room and a reader are recommended. Because ultrasonic waves cannot penetrate walls and solid objects. Easy to use: Simply plug this indoor fly trap into an outlet and get to work. Ultrasonic repellents should be installed 10-50 inches off the ground and perpendicular to the floor. Safe for the environment: This repellent is safer than traditional insect repellents instead of harmful and dangerous chemical poisons. Humans and pets cannot hear the ultrasound. Clean the environment: Very effective in controlling pests and keeping them out of your home or office. No more insect carcasses around in the morning. Working hours: Unlike chemical sprays, electronic repellents do not work right away. Depending on the number of pest infestations, it usually takes 3 to 4 weeks. Package Includes:1 Set of 2 Insect Repellents Specification:Material: ABSSize: as shownNet Weight: 100g Notes:Due to manual measurement, please allow an error of 1-2cm.Due to the differences between different monitors, the pictures may not reflect the actual color of the item.