Ef012 additional sensor for measuring current up to 200 amperes. Works with the elite or e2. Perfect for whole house applications where a 200 ampere service is installed. Split core design easily fits around wire sizes up to #4/0 AWG without breaking connections. An additional sensor is be required if measuring 3 phase power. The extra large sensor should be purchased for use on cables that are over 12mm in diameter, and up to 19mm in diameter.