All Ubiquiti airMAX devices are equipped with ESD protection. However, to protect outdoor devices, and to meet certain local code requirements, installing the ETH-SP-G2 is recommended as an additional layer of protection. To guard against costly service calls, and to help your subscriber installations meet code requirements, you install two ETH-SP-G2s: one near the CPE, and the other at the entry point to the building. Damaging ESD attacks and surges will be absorbed by the ETH-SP-G2s and safely discharged into the ground.