Keep You Away From Dark• EXCELFU generator interlock kit is a device designed to allow safe back feeding of a home by a portable generator during a power outage. This eliminates unsafe generator back feeding situations that could potentially electrocute electric power company workers or destroy the generator. When an interlock switch is installed, it prevents the generator circuit breaker and the main circuit breaker from both being on at the same time. An generator interlock kit is a safe and cost-effective way to ensure you're using a portable generator safely.• EXCELFU generator interlock kit consist of two metal plate and interlock together by three bolts. When move down, the plate stop the generator back feed circuit breaker and allows the main breaker to remain on. When move up, the generator back feed circuit breaker may be turned on but the main circuit breaker is blocked and will remain off.Feature• Compatible with Eaton/Cutler Hammer BR Series, BR series with plug-in neutral and CH-series with plug in neutral 150 and 200 amp • Do Not Require A Separate Generator Panel• Easy to install and include everything you needPackage Include1 x Interlock Plate3 x Shoulder Screws3 x Hex Nuts1 x Drill Bit1 x Generator Start-Up Procedure Label5 x Remind Label2 x Zip Ties1 x Instruction