dip switch electric shield
As I mentioned in a comment, that is actually a reed relay. The package it comes in is called DIP (dual in-line package) since it conforms to a certain spacing on the pins. The purpose of the electrostatic shield in the context of the relay is to reduce interference on the signal going through the relay when the relay coil engages (which generates a magnetic field and can induce a current in the relay contacts). The resulting current appears as noise in the signal, especially if the signal is being measured by something either very sensitive or fairly high-impedance.
Quoting from an application note I found after googling, which notes how to connect the shield:

Electrostatic Shield
Used to reduce any noise or electrostatic coupling that may
occur between the coil of a relay and the internal magnetic
reed switch. The electrostatic shield normally consists of
copper, terminated to a designated pin externally connected
to ground.

Source: http://m.littelfuse.com/~/media/electronics/application_notes/reed_switches/littelfuse_magnetic_sensors_and_reed_switches_catalog_glossary_reed_switch_terms_application_note.pdf.pdf