Features MAIN PURPOSE: This kit can prevent both mains and generator power from being turned on at the same time, avoiding the inconvenience caused by unexpected power outages. APPLICABLE MODEL: Generator interlock kit is suitable for D QO and for 150 and 200 Amp panels. ENSURE SAFETY: This interlock kit is designed to safely direct generator power to any circuit in your home, while ensuring that you can safely use all household appliances. REQUIRED INSTALLATION SPACE: The spacing between the main circuit breaker and the generator circuit breaker needs to 1 3/8 inch. EASY TO INSTALL: The interlock kit comes with 3/16 drill bit, is easy to install without requiring additional control boxes or wiring. Specification: Item Type: Generator Interlock Kit Material: Aluminum Alloy Model: SD200A Package List:2 x Generator Interlock Panel3 x Nut3 x Screw1 x Drill Bit2 x Cable Tie2 x Sticker1 x User Manual Package List 2 x Generator Interlock Panel 3 x Nut 3 x Screw 1 x Drill Bit 2 x Cable Tie 2 x Sticker 1 x User Manual